Method for Controlling a Headlamp System for a Vehicle, and Headlamp System

ABSTRACT

In a method for controlling a headlamp system of a vehicle, road users are detected in front of the vehicle in the driving direction, and a total light pattern produced by the headlamp system is controlled such that it provides an illumination range in the direction of at least one detected road user that is less than the distance to the detected road user, and which provides an illumination range in another direction that is greater than the distance to the detected road user. The illumination range in the other direction is controlled as a function of the horizontal angle between the driving direction of the vehicle and the connecting line from the vehicle to the detected road user or to another detected road user.

FIELD OF THE INVENTION

The present invention relates to a method for controlling a headlampsystem for a vehicle; it also relates to a headlamp system for a vehicleequipped with a control unit.

BACKGROUND INFORMATION

When the visual conditions are poor, especially in the dark, it is thetask of the headlamps of a vehicle to illuminate the environment infront of the vehicle in the driving direction, in particular theroadway. In addition, the headlamps serve to identify the vehicle toother road users.

For the light emission in the driving direction, it is conventional toprovide headlamps which are able to offer a low beam functionality and ahigh beam functionality. The high beam functionality produces a verycomprehensive illumination of the environment. However, it has thedisadvantage of blinding other road users, in particular the drivers ofvehicles driving ahead and of vehicles approaching from the oppositedirection. The low beam, on the other hand, makes it possible togenerate a light pattern that does not blind other road users, but theillumination of the environment is much lower than in the high beamfunctionality. Due to the very high traffic densities that havedeveloped in the meantime, the high beam functionality can be used onlyrarely nowadays. As a consequence, headlamp systems are needed whichoffer better illumination than the conventional low beam functionality,but which do not blind other road users in the way the high beamfunctionality does.

One method for controlling a headlamp system for a vehicle is describedin German Published Patent Application No. 10 2007 045 150. In this casethe headlamp system includes two headlamps, which are situated at adistance from each other and emit a combined light beam in order togenerate a total light pattern. In addition, the headlamps are equippedwith a diaphragm array, whose position is variable in order to modifythe total light pattern. In the method, a road user is detected in thedirection of the light emission of the headlamp system. If such a roaduser has been detected, the position of at least one diaphragm array ismodified such that a center region having a lower illumination range, aswell as side regions, which are adjacent to this center region and havea greater illumination range, are formed in the total light pattern onboth sides in the direction of the detected road user. The illuminationrange in the center region, in particular in the direction of thedetected road user, is controlled as a function of the vertical angle,that is to say, the distance of the road user. The light pattern isgenerated exclusively by modifying the position of the diaphragms of thediaphragm array, and possibly by pivoting the light emission directionof the headlamps about a vertical axis.

German Published Patent Application No. 10 2007 028 658 describesanother method for controlling a headlamp system of a vehicle. In thiscase the headlamp system has a right and a left headlamp unit, bothbeing equipped with separate headlamps for a low beam and a high beamlight. In the method, a road user is detected in the direction of thelight emission of the headlamp system. Once such a road user has beendetected, the light pattern generated by the headlamps for the high beamis modified with regard to the lateral illumination, whereas the lightpattern for the low beam produced by the separate headlamps remainsunchanged.

Finally, a system for generating a light bundle in the movement regionin front of the vehicle is described in German Published PatentApplication No. 10 2007 040 042. The system is made up of a headlamphaving an LED field provided with a plurality of light diodes, which areelectrically controllable individually. In addition, the system has anobject detection device for detecting objects in the vicinity of themotor vehicle, and a position determination device for determining theposition of a detected object in relation to the motor vehicle. In thissystem the individual light diodes are controlled in such a way that alimit value for a luminous intensity in the region of a detected objectis not exceeded.

SUMMARY

Example embodiments of the present invention provide a method and aheadlamp system, with whose aid a total light pattern may be generatedwhich illuminates the environment of the vehicle as best as possible butdoes not blind other road users.

According to example embodiments of the present invention, a method forcontrolling a headlamp system of a vehicle is provided, in which theheadlamp system has two headlamps situated at a distance from eachother, and in which road users are detected in front of the vehicle inthe travel direction. Furthermore, a first total light pattern may beproduced, in which the illumination range on a first side of a centeraxis is greater than on the other, second side of this center axis.Furthermore, a second total light pattern is able to be produced, inwhich the total light pattern is controllable such that it has anillumination range in the direction of at least one detected road userthat is less than the distance to the detected road user, and which hasan illumination range in another direction that is greater than thedistance to the detected road user. A characteristic of the method isthat in the switchover from the first total light pattern to the secondtotal light pattern, the illumination range of at least one headlamp onthe first side of the center axis is initially reduced to at least suchan extent that it is less than the distance to the detected road user,the second total light pattern being produced subsequently.

The center axis, in particular, is the separating line between the roadlanes on a straight roadway. In this case the first side of this centeraxis represents the right lane, and the second side of this center axisrepresents the left, opposite driving lane. In left-hand driving thesides are reversed.

Thus, different total light patterns in the different aspects may beprovided. Moreover, there is back-and-forth switching between thesetotal light patterns. The total light patterns are defined in thefollowing text:

The first total light pattern is asymmetrical especially with regard toa longitudinal axis when considering the form of the light-dark cutoffon the road. On the side of the own lane, i.e., on the first side of thecenter axis, an illumination range is provided that is greater than onthe side of the adjacent lane, which represents the oncoming trafficlane on roads having one lane in each direction. On the adjacent lane,the illumination range in particular extends only to a cut-off boundary,so that oncoming road users will not be blinded. The first total lightpattern, for example, constitutes a generally known low-beam lightpattern. When looking at the light-dark cutoff on a screen situatedperpendicularly to the longitudinal vehicle axis, a characteristic 15°increase comes about in the light-dark cutoff in relation to thehorizontal line in the low-beam light pattern on the driving side. This15° increase corresponds to the greater illumination range on thedriving side of the vehicle.

A particular characteristic of the second total light pattern, which isalso referred to as masked permanent high-beam, is a control of theillumination range as a function of a detected road user or a pluralityof detected road users. The illumination range in the direction of sucha road user, or in the direction of a plurality of such road users,i.e., in a region having an opening angle which is defined by the widthand the distance of the detected road user(s), is less than the distanceto the detected road user(s). The distance is defined such that the roaduser will not be blinded by the second total light pattern. For example,if the detected road user is another vehicle, then the distance mayextend to the bumper of the other vehicle. If the other road user is abicyclist or pedestrian, then the distance may be defined such that itextends to the point at which the other road user makes contact with theground.

The masked permanent high beam provides an illumination range in anotherdirection that is greater than the distance to the detected road user,the different direction especially being a region laterally adjacent tothe opening angle that includes the detected road user. A center regionis formed in the second total light pattern, which, in particular, has alower illumination range in the direction of the detected road user, andside regions which have a greater illumination range are formed on bothsides adjacent to this center region. This provides an optimalillumination of the environment of the vehicle in the driving directionfor the masked permanent high beam, but ensures that road users in frontof the vehicle in the travel direction will not be blinded. When viewingthe light-dark cutoff of the masked permanent high beam on a measuringscreen situated at a right angle, a horizontal light-dark cutoff isformed in front of the detected road user, in particular, and aperpendicular light-dark cutoff, which corresponds to the greaterillumination range in the region adjacent to the detected road user, isformed along the sides of the detected road user. The illumination rangein the center region, which, in particular, extends to the detected roaduser in the second total light pattern, is preferably controlled by analready provided illumination range control.

Finally, a third total light pattern, which hereinafter is also referredto as sliding illumination range, may be provided. In the slidingillumination range, the maximum illumination range is controlled suchthat it extends to a detected road user. In this case, the illuminationrange thus is less than the distance to the detected road user, and theillumination range is not static but controlled as a function of thedistance of the detected road user. However, in contrast to the maskedpermanent high beam, no vertical light-dark cutoff in the center of thetotal light pattern is produced in the sliding illumination range.

The term illumination range denotes an angle-dependent distance on theroad, at which the light intensity drops below a limit value. The limitvalue for the light intensity is defined in the same manner as in thelight-dark cutoff. At distances that exceed the illumination range, thelight intensity particularly is so low that other road users will nolonger be blinded. The angle especially is a horizontal angle, which isformed by a longitudinal axis through a headlamp or a headlamp system onthe one side, and a connecting line from a point on the light-darkcutoff and the intersection of the longitudinal axis with a transverseaxis extending through the headlamp or the headlamp system.

The total light patterns may be produced by superimposing a firstpartial light pattern of the first headlamp and a second partial lightpattern of the second headlamp. When switching from one total lightpattern to the other total light pattern, in particular when switchingfrom the first total light pattern to the second total light pattern,the illumination range of at least the second headlamp, in particular ofboth headlamps, is reduced on the first side of the center axis. Thelight emission direction of the second headlamp is then pivoted about aperpendicular pivot axis in order to produce the second total lightpattern.

If the second total light pattern, i.e., the masked permanent high beam,is produced by pivoting the light emission direction of the leftheadlamp outwardly, away from the light-emission direction of the rightheadlamp in right-hand traffic, so that the angle between the lightemission directions of the two headlamps becomes greater, and if theleft headlamp on the right side of the center axis, i.e., on the side ofthe road lane, has a greater illumination range than on the left side ofthe center axis, i.e., on the oncoming traffic lane, there arises theproblem that another road user may be blinded when the light cone of theleft headlamp is pivoted. To prevent this, the greater illuminationrange is initially reduced on the first side of the center axis in themethod described herein. Only then will the light emission direction bepivoted in an outward direction.

For example, the reduction of the illumination range prior to producingthe masked permanent high-beam may be realized in that the headlampsystem provides a so-called city-light functionality. A characteristicof the city-light functionality is that it provides a symmetrical totallight pattern which has a limited illumination range, the illuminationrange being lower than the maximum illumination range of the first totallight pattern, i.e., the low-beam, for example. The second headlamp maythen be pivoted outwardly, as in a cornering light functionality. Thesecond total light pattern is produced subsequently.

If a reverse operation takes place, i.e., a switch from the second totallight pattern, which is the masked permanent high beam, to the firsttotal light pattern, i.e., to low beam, for instance, a city-lightpattern is produced to begin with, whereupon the second headlamp, andpossibly also the first headlamp, is/are pivoted about a perpendicularpivot axis, and the asymmetrical first total light pattern is generatedonly subsequently. In this manner blinding of other road users is alsoprevented in the switch back to the first total light pattern.

According to example embodiments of the present invention, a headlampsystem for a vehicle is provided in addition. The headlamp systemincludes at least two headlamps, set apart from each other, forproducing a total light pattern. Furthermore, the headlamp systemincludes a device for detecting road users in front of the vehicle inthe driving direction, and a control unit, which is coupled to the roaduser detection device and is able to produce a first total lightpattern, in which the illumination range on a first side of a centeraxis is greater than on the other, second side of this center axis; itis also able to produce a second total light pattern in which the totallight pattern is able to be controlled such that it has an illuminationrange in the direction of at least one detected road user that is lessthan the distance to the detected road user and which has anillumination range in another direction that is greater than thedistance to the detected road user. It is characteristic of the methodthat in the switchover from the first total light pattern to the secondtotal light pattern, the control unit is able to control the headlampssuch that the illumination range of at least one headlamp on the firstside of the center axis is initially reduced, to at least such an extentthat it is less than the distance to the detected road user, the secondtotal light pattern being produced subsequently.

The headlamp system may be able to execute the method either completelyor partially.

A first aspect of example embodiments of the present invention, inparticular, relates to the transition from an asymmetrical lightpattern, such as a low beam, to the so-called masked permanent highbeam. The method and the headlamp system, in particular, ensure thatanother road user will not be blinded in the switchover between thesetwo total light patterns.

According to example embodiments of the present invention, a method forcontrolling a headlamp system for a vehicle is provided, which detectsroad users in front of the vehicle in the travel direction. In themethod, the headlamp system is able to produce a third total lightpattern, in which the light pattern may be controlled such that it hasan illumination range in the direction of a detected road user that isless than the distance to the detected road user, and that is greaterthan, or equal to, the illumination range in other directions.Furthermore, a second total light pattern is able to be produced, inwhich the total light pattern is controllable such that it has anillumination range in the direction of at least one detected road userthat is less than the distance to the detected road user, and which hasan illumination range in another direction that is greater than thedistance to the detected road user. A characteristic of the method isthat during the switchover from one total light pattern to another totallight pattern, the illumination range in the direction of the detectedroad user is controlled by pivoting the light emission direction of theheadlamp system about a horizontal axis, such that the illuminationrange extends to the detected road user.

According to example embodiments of the present invention, a headlampsystem for a vehicle is furthermore provided, which has at least twoheadlamps, set apart from each other, for generating a total lightpattern; it also has a device for detecting road users in front of thevehicle in the driving direction. In addition, the headlamp systemincludes a control unit, which is coupled to the road user detectiondevice and is able to produce a third total light pattern in which thelight pattern is controllable such that it has an illumination range inthe direction of a detected road user that is less than the distance tothe detected road user and greater than, or equal to, the illuminationrange in other directions. Furthermore, a second total light pattern isable to be produced, in which the total light pattern is able to becontrolled such that it has an illumination range in the direction of atleast one detected road user that is less than the distance to thedetected road user, and it has an illumination range in anotherdirection that is greater than the distance to the detected road user.The headlamp system is characterized by an illumination range control,by which, during the switchover from one total light pattern to anothertotal light pattern, the illumination range in the direction of thedetected road user is able to be controlled by pivoting the lightemission direction of the headlamp system about a horizontal axis, suchthat the illumination range extends to the detected road user.

The second total light pattern, in particular, is the afore-mentionedmasked permanent high beam. The third total light pattern, inparticular, is the afore-mentioned sliding illumination range. In theswitchover between these two total light patterns, it is ensured inparticular that the illumination range continuously extends to thedetected road user. In this manner the use of the method and theheadlamp system provides a permanent and excellent illumination whichextends to a detected road user in a simple and cost-effective manner.

The illumination range control of the headlamp system in particularincludes a first actuator for pivoting the light emission direction ofat least one headlamp about a horizontal axis. Moreover, the headlampsystem may have a second actuator for pivoting the light emission deviceof at least one headlamp about a vertical axis. This actuator, forexample, may be an actuator which is already provided for a corneringlight functionality.

According to example embodiments of the present invention, the headlampsystem includes a diaphragm system for the headlamps that has at leasttwo planar diaphragms, which are movable in the vertical and/orhorizontal direction. In the second total light pattern, i.e., in themasked permanent high beam, the side regions form a vertical light-darkcutoff with respect to the center region, which is able to be producedby modifying the vertical position and/or the horizontal position of atleast one of the two diaphragms. To displace the two diaphragmsvertically and horizontally, the headlamp system in particular has athird actuator, which is jointly coupled to both diaphragms, inparticular. In this manner it is possible for the different total lightpatterns to be generated by only three actuators. As a result, theheadlamp system is able to be manufactured and operated in acost-efficient manner.

According to example embodiments of the present invention, a method forcontrolling a headlamp system for a vehicle is provided, in which theheadlamp system is able to produce at least two total light patterns andallows a switch between the total light patterns. In the method, thedriving behavior is recorded and when a switch takes place from onetotal light pattern to another total light pattern, the time intervalfor the transition from the one total light pattern to the other totallight pattern is determined as a function of the driving behavior.

In this method, a road user is detected in front of the vehicle in thedriving direction, in particular, and a total light pattern produced bythe headlamp system is controlled such that it has an illumination rangein the direction of at least one detected road user that is less thanthe distance to the detected road user, and which has an illuminationrange in another direction that is greater than the distance to thedetected road user. This total light pattern, in particular, is theafore-mentioned second total light pattern, i.e., the masked permanenthigh beam.

The driving behavior is determined especially by the driving dynamicsand/or the magnitude of the vehicle acceleration, especially themagnitude of the absolute value of the vehicle acceleration. The greaterthe driving dynamics, i.e., especially the greater the acceleration orthe absolute value of the acceleration, the shorter the time intervalfor the transition from one total light pattern to another total lightpattern.

This configuration ensures that the transition times are adapted to thedriving dynamics, which leads to a switch between the total lightpatterns that the user perceives as pleasant.

Time interval ΔT is calculated as a function of acceleration B, inparticular in the following manner:

ΔT=−k ₁ ·abs(B)+k ₂,

where k₁

0.3s³/m≦k ₁≦2.0s³/m

where k₂

2s≦k₂≦10s

where k₁

0.5s³/m≦k ₁≦0.9s³/m

and where k₂

4s≦k₂<6s

In particular, k₁=0.7 s³/m and k₂=5 s.

In addition, the driving behavior may be determined as a function of thedriver type. When determining the driver type, the driver may beidentified first. Current and possibly also historical data inconnection with the driver are then called up, whereupon a particulardriver type is assigned to the driver.

Moreover, the user has the option of freely selecting the drivingbehavior. For example, the driver may define the desired drivingbehavior prior to the start of a trip, via input.

According to example embodiments of the present invention, a headlampsystem for a vehicle is furthermore provided, which includes at leasttwo headlamps, situated at a distance from each other, for generating atotal light pattern; it also includes a control unit with whose aid itis possible to produce at least two total light patterns and with whoseaid it is possible to switch between the total light patterns. Theheadlamp system furthermore includes a detection device for detectingthe driving behavior. The headlamp system is characterized by a timer;in the switchover from one total light pattern to another total lightpattern, the timer is able to determine the time interval for thetransition from the one total light pattern to the other total lightpattern as a function of the driving behavior.

The two total light patterns may be the first and the second, the firstand the third, and the second and the third previously mentioned totallight pattern.

The time interval for the transition from one total light pattern toanother total light pattern is allowed to take place such that anoptimal illumination of the environment of the vehicle is achieved as afunction of the driving behavior.

According to example embodiments of the present invention, a method forcontrolling a headlamp system of a vehicle is provided, which detectspreceding or oncoming road users in front of the vehicle in the drivingdirection and controls the light pattern produced by the headlamp systemsuch that it provides an illumination range in the direction of adetected preceding road user that is less than the distance to thedetected preceding road user, and whose illumination range in thedirection of the adjacent road lane is switched back and forth as afunction of the detection of another, in particular an oncoming, roaduser, the switch taking place between at least a first illuminationstate having greater illumination of the adjacent road lane, and asecond illumination state having lower illumination of the adjacent roadlane. The method is characterized by the fact that the switch betweenthe two illumination states for the illumination range in the directionof the adjacent road lane is delayed as a function of the detection rateof the additional road users, in particular oncoming road users.

The light pattern produced by the headlamp system, in particular, is theafore-mentioned second total light pattern, i.e., the masked permanenthigh beam. In the two illumination states of this total light pattern,the illumination range of a side region adjacent to a first detectedroad user is adapted as a function of the detection of another road userin the method described herein. If the adaptation goes so far that theillumination range in the side regions corresponds to the illuminationrange of the center region of the masked permanent high beam, then thishas the result that the first illumination state of the light patterncorresponds to the masked permanent high beam and the secondillumination state corresponds to the light pattern of theafore-mentioned third total light pattern, i.e., the slidingillumination range.

In particular, the more frequently additional road users are detected,especially oncoming road users, the greater the delay time. With eachdetected further road user, for instance, the delay time is extended byan extension interval and the delay time is shortened using a definedtime reduction rate. If necessary, however, a minimum value and amaximum value may be specified for the delay time, so that the delaytime does not become arbitrarily long when very high traffic density isencountered. The special selection of the delay time ensures that apleasant illumination pattern is produced for the driver, which does notbecome distracting as a result of excessive changes.

Furthermore, it is possible to define the extension interval as afunction of the particular horizontal angular position at which theadditional, in particular oncoming, road user has been detected. Morespecifically, it may be taken into account whether the road user appearson the left or right side or in the center in front of the vehicle.Finally, the extension interval and/or the reduction rate may also bedetermined as a function of the vehicle speed. For example, in a speedrange that is typical for county roads, the delay time may be increasedonly slowly when oncoming road users are detected, but lowered rapidly.In contrast, at high speeds as they are typically encountered on anexpressway, a newly detected additional road user may cause aconsiderable extension of the delay time, the reduction of the delaytime through the reduction rate being implemented slowly.

For instance, the delay time lies within a range of one second to 400seconds, in particular within a range of 2 seconds to 200 seconds.

According to example embodiments of the present invention, in the lightpattern in the direction of the detected road user, a center regionhaving a low illumination range and, adjacent to this center region onboth sides, a first and a second side region having a greaterillumination range are formed when no oncoming road user has beendetected. In this case, a masked permanent high beam is thereforeprovided, in which the second side region illuminates the adjacent roadlane. If the first, i.e., the right side region, has a greaterillumination range than the center region, the reduction rate in such acase is greater than in cases where the first side region has a lowerillumination range than the center region or the same illumination rangeas the center region. In this case the adjacent lane is thereforereilluminated more rapidly when the other side region of the maskedpermanent high beam is fully illuminated. Under these circumstances, theillumination of the first side region is activated or deactivated alsoas a function of the detection of a road user, in particular. Overall,the method hereof makes it possible for the most part to provide acalmer light pattern when the traffic volume is higher.

According to example embodiments of the present invention, the curvatureof the road is determined, and if the curvature exceeds a limit value, aswitch to the second illumination state takes place, which provides fora lower illumination of the adjacent lane. The curvature of the road maybe determined from data ascertained by sensors of the vehicle, such asthe temporal change of the steering angle, or with the aid of thecurrent position of the vehicle and a digital geographical map availablein the navigation system, for instance.

According to example embodiments of the present invention, a headlampsystem for a vehicle is furthermore provided, which has at least twoheadlamps, set apart from each other, for generating a total lightpattern, and a device for detecting road users driving in front of thevehicle in the driving direction, as well as oncoming road users.

In addition, the headlamp system includes a control unit, which iscoupled to the road user detection device and with whose aid a totallight pattern is able to be generated which is controllable such that ithas an illumination range in the direction of a detected preceding roaduser that is lower than the distance to the detected preceding roaduser; furthermore, its illumination range in the direction of theadjacent road lane is switched back and forth as a function of thedetection of an oncoming road user, the switch taking place between atleast a first illumination state providing greater illumination of theadjacent road lane, and a second illumination state providing lowerillumination of the adjacent road lane. The headlamp system ischaracterized by the fact that the control unit has a delay unit, whichmakes it possible to delay the switch between the two illuminationstates for the illumination range in the direction of the adjacent laneas a function of the detection rate of oncoming road users.

Thus, excessive back-and-forth switching between different lightpatterns may be prevented. This calms the produced light patterns andavoids distraction of the driver by the changes in the light patterns.

According to example embodiments of the present invention, a method forcontrolling a headlamp system of a vehicle is provided, by which theroad user is detected in front of the vehicle in the driving direction,in particular, and a total light pattern produced by the headlamp systemis controlled such that it provides an illumination range in thedirection of at least one detected road user that is less than thedistance to the detected road user, and which provides an illuminationrange in another direction that is greater than the distance to thedetected road user. The method is characterized by the fact that theillumination range in the other direction is controlled as a function ofthe horizontal angle between the driving direction of the vehicle andthe connecting line from the vehicle to the detected road user or toanother detected road user. The light pattern produced by the headlampsystem in particular is the afore-mentioned second total light pattern.

The smaller the horizontal angle, the greater the illumination range,especially in the other direction. The following may hold true forillumination range L in the other direction:

LW=L _(max)(−mΦ+n),

L_(max) being the maximum illumination range, Φ being the horizontalangle, and the following applying to m:

0.167 deg⁻¹ ≦m≦0.4 deg⁻¹,

In particular:

0.2 deg⁻¹ ≦m≦0.3 deg⁻¹

and especially preferably,

m=0.25 deg⁻¹

and for n:

1≦n≦1.2,

In particular:

1.1≦n≦15

and especially preferably,

n=1.125.

In addition, it may be provided that the illumination range correspondsto the maximum illumination range up to a particular angle, and that theillumination range is minimal starting at a particular angle. Forhorizontal angles Φ≦Φ₁ the illumination range in the other directioncorresponds to the maximum illumination range, Φ₁ lying in a range of 0°to 2°, in particular 0.2° to 0.8°. Furthermore, for horizontal anglesΦ≦Φ₂ the illumination range in the other direction corresponds to theminimum illumination range, Φ₂ lying in a range of 3° to 6°, inparticular from 4° to 5°.

With the aid of the afore-mentioned parameters, it is possible to ensurethat the reduction in the illumination range when an oncoming road useris encountered, or when a road user is passed, does not occur tooabruptly. This measure, too, contributes to a calmer light pattern.

The illumination range in the other direction is controlled inparticular as a function of the horizontal angle between the drivingdirection of the vehicle and the connecting line from the vehicle to theother detected road user. In this case, the light pattern illuminatesthe opposite road lane, among other things.

Furthermore, the illumination range in the other direction is able to becontrolled as a function of the horizontal angle between the drivingdirection of the vehicle and the connecting line from the vehicle to thedetected road user. In such a case, in a passing maneuver, the lightpattern in the other direction illuminates the region adjacent to theroad lane of the detected road user, that is to say, the right regionadjacent to the road user being passed in right-hand traffic. Thecontrol of the illumination range in the other direction may beimplemented in particular once a signal has been set for a passingmaneuver in the direction of the opposite driving lane, e.g., the turnsignal indicator was actuated in the direction of the oncoming trafficlane.

According to example embodiments of the present invention, a centerregion that provides a lower illumination range and, adjacent to thiscenter region on both sides, side regions that provide a greaterillumination range are formed in the light pattern in the direction ofthe detected road user, i.e., the second total light pattern isprovided. In this case the illumination range in a side region iscontrolled as a function of the horizontal angle between the drivingdirection of the vehicle and the connecting line of the vehicle and thedetected road user or the additional detected road users.

When controlling the illumination range as a function of the horizontalangle, a hysteresis may be run through as well in the individual case.

According to example embodiments of the present invention, a headlampsystem for a vehicle is furthermore provided, which has at least twoheadlamps, set apart from each other, for generating a total lightpattern; it also has a device for detecting a road user in front of thevehicle in the driving direction. The headlamp system furthermoreincludes a control unit, which is coupled to the road user detectiondevice and with whose aid a total light pattern is able to be produced,which is controllable such that it has an illumination range in thedirection of at least one detected road user that is less than thedistance to the detected road user, and which has an illumination rangein another direction that is greater than the distance to the detectedroad user. The headlamp system is characterized by the fact that theheadlamps are controllable with the aid of the control unit, such thatthe illumination range in the other direction is able to be controlledas a function of the horizontal angle between the driving direction ofthe vehicle and the connecting line from the vehicle to the detectedroad user or to another detected road user.

Thus, the light pattern may be controlled especially when a vehicle isdriving in front of the own vehicle and when another vehicles approachesfrom the opposite direction, or the own vehicle is passing a vehicledriving ahead. In such a case it is ensured that the produced totallight pattern does not change too abruptly.

According to example embodiments of the present invention, a method forcontrolling a headlamp system for a vehicle is provided, in which atleast two total light patterns are able to be produced and aback-and-forth switch between the total light patterns is possible. Inthe method, road users in front of the vehicle in the driving directionare detected. Thus, one of the two total light patterns is selected as afunction of the detection rate of other road users.

The method may ensure that a specific total light pattern is able to beproduced when the traffic density is too high, i.e., when a high numberof road users is detected within a time interval. The two total lightpatterns are, in particular, the afore-mentioned second total lightpattern, i.e., the masked permanent high beam, and the third total lightpattern, i.e., the sliding illumination range. If the detection rateexceeds a specific limit value, then the sliding illumination range isproduced as the total light pattern. It can then be prevented that theareas of the masked permanent high beam that have a very highillumination range must be activated and deactivated too frequently.

The total light pattern may be selected as a function of the position ofother detected road users and/or the vehicle speed. For example, a firststep size is produced with each detected road user. The first step sizesproduced with each detected road user are integrated, and a second stepsize, which is a function of the vehicle speed, is subtracted from theintegrated step size. This generates a first output signal, whichcharacterizes one of the total light patterns. The first step size mayadditionally depend on the vehicle speed as well.

According to example embodiments of the present invention, the selectionof the total light pattern alternatively or additionally is made as afunction of temporal steering angle changes of the vehicle. Inparticular, a first steering angle value is produced as a function ofchanges in the steering angle. Furthermore, a second steering anglevalue is produced as a function of the vehicle speed and the steeringangle. A second output signal, which characterizes one of the overalllight patterns, is then produced as a function of the value of the firstand the second steering angle. Taking the temporal steering anglechanges into account makes it possible to detect a winding roadway. Onwinding roads, the use of certain total light patterns, such as themasked permanent high beam, is disadvantageous. When traveling onwinding roads, the method makes it possible to produce a total lightpattern that is suitable for roads of this type. For example, a slidingillumination range may be produced under these circumstances.

According to example embodiments of the present invention, the thirdtotal light pattern is generated when the first and the second outputsignal characterize this total light pattern. Moreover, when switchingback and forth between both total light patterns, a hysteresis may berun through in order to prevent excessive switchovers.

According to example embodiments of the present invention, a headlampsystem for a vehicle is furthermore provided, which has at least twoheadlamps, set apart from each other, for generating two total lightpatterns; it also has a control unit, which is able to switch back andforth between the two total light patterns, and a device for detectingroad users in front of the vehicle in the driving direction. One of thecharacteristics of the headlamp system is that the control unit isdesigned to allow one of the two total light patterns to be selected asa function of the detection rate of other road users.

In particular, the headlamp system may be able to execute the steps ofthe method, either completely or partially.

The following text describes features and aspects of example embodimentof the present invention, which are able to be combined. Furthermore,the example embodiments described herein are combinable with each otherin various manners.

In example embodiments of the present invention, the switchover from onetotal light pattern to another total light pattern takes placeautomatically, especially as a function of the detection of a road user.In addition, it is also possible that the switchover from one totallight pattern to another total light pattern is triggered by anactuating action of a user.

According to example embodiments of the present invention, the energyconsumption of at least one total light pattern is adjustable. Thesecond total light pattern, in particular, is able to be operated in anenergy-saving mode, as so-called high beam assistant, which switchesback and forth only between low beam and conventional high beam lights.Energy is saved in this energy-saving mode because of the reducedmovement frequency, in particular the less frequent operation ofactuators.

In the method according to example embodiments of the present invention,it may furthermore be detected whether travel is taking place on amulti-lane road. A multi-lane road means that multiple adjacent drivinglanes are assigned to the same driving direction. If a multi-lane roadhas been detected, a switch is made to an illumination state for theadjacent road lane, in which this neighboring lane is illuminated usinga lower illumination range. For instance, it is possible to switch tothe third total light pattern for the sliding illumination range.

According to example embodiments of the present invention, a hysteresisis run through in the back-and-forth switch between two total lightpatterns. In particular, a hysteresis is run through during theback-and-forth switch between the two illumination states for theillumination range in the direction of the adjacent lane. Because ofthis, excessive back-and-forth switching between two total lightpatterns is avoided. This leads to a calmer light pattern.

In the method and in the headlamp system, other road users aredetectable with the aid of a camera, in particular a CCD camera havingdownstream image processing software, and/or a laser, infrared and/orradar sensor. These sensors detect whether another road user is presentin a detection range. If this is the case, the position of the otherroad user in relation to the own vehicle is detected in addition. Thismakes it possible to detect not only illuminated road users, but alsoroad users who have no light sources of their own, such as pedestrians,for instance.

In all of the afore-mentioned aspects, the road user, provided it is anilluminated vehicle, is able to be detected in front of the vehicle inthe driving direction, in particular by recording an image of a trafficarea in the visible spectral range, extracting from the image cohesiveareas having a brightness that exceeds a threshold value, classifyingthe areas at least as a function of their size, forming a confidencevalue for each area, which represents a measure for the similarity ofthe area of the image to a vehicle light, based on the classification ofthe area and a physical quantity assigned to the area, and finally,making a determination as to whether an area is assigned to a vehiclelight as a function of the confidence value.

The method takes into account that bright areas of the image that comefrom very distant light sources differ from bright areas that come fromclose light sources. The bright areas of the images are classified basedon this differentiation. However, since the classification in many casesdoes not allow a clear assignment of an area to a vehicle light, aconfidence value is subsequently determined, at least for the areas thatcannot be unequivocally assigned to a vehicle light. Based on thisconfidence value it is then possible to determine in very reliablemanner whether an area may be assigned to a vehicle light.

According to example embodiments of the present invention, aclassification value is obtained from characteristics of this area inthe classification. This classification value is assigned to each area,and the confidence value is formed from the classification value of thearea and the physical quantity. The classification value describes howwell, or how unequivocally, the area is able to be assigned to theparticular class in the classification. Therefore, the classificationvalue represents a differentiation within a class.

Characteristics for each region, in particular, are determined for theclassification. These characteristics may include, for example, thebrightness of the area, the form or outline of the area, and/or thecolor within the area. In addition, the characteristics may includevalues for the center of mass, the dimension and/or the main axes of thearea, and additionally or alternatively, values for the intensity ofmonochromatic pixels of the area. For the intensity of monochromaticpixels of the area, the maximum intensity, a mean value, the standarddeviation, the position of the maximums within the area, thedistribution of the histogram, and/or the value of the average gradientmay be taken into account. Furthermore, as an alternative or inaddition, these values may be determined only for pixels of one colorthat corresponds to the color of a tail light of a vehicle, i.e., red inthe standard case.

Moreover, it is possible to consider characteristics which may be usedto obtain color information indirectly, by defining various comparisonsbetween monochromatic and red pixels, such as the ratio between the meanvalue of the monochromatic level and the average value of the red level.“Monochromatic” in this context also denotes the gray-scale value or thebrightness in this area.

Finally, the use of the method allows a mean value of thecharacteristics to be formed while taking a plurality of consecutiveimages into account.

According to example embodiments of the present invention, theclassification values of the areas are obtained with the aid of alearning algorithm, and the classification values are subsequentlyassigned to discrete weighted classification values. The confidencevalue is then formed from the weighted classification value of the areaand the physical quantity.

According to example embodiments of the present invention, the physicalquantity utilized when forming the confidence value is the maximumgray-scale value within the area, in particular the maximum gray-scalevalue within the area normalized across the maximally possiblegray-scale value. When the confidence value is determined in this mannerit is taken into account that vehicles that are in closer proximity tothe own vehicle generate brighter areas in the image than vehicles at agreater distance. Accordingly, areas assigned to vehicles that are inthe vicinity of the own vehicle have a higher confidence value thanareas assigned to vehicles at a greater distance. Furthermore, a brightarea caused by a reflection of the own vehicle lights receives a lowerconfidence value, and this confidence value is reduced even further ifthe reflection is caused by an infrastructure element that is located ata great distance.

Whether an area may be assigned to a vehicle light or a vehicle to thelights is already determined on the basis of the classificationaccording to example embodiments of the present invention. Theconfidence value is then formed only for those areas to which a vehiclelight cannot be assigned unequivocally based on the classification.

According to example embodiments of the present invention, theenvironment of the areas may be examined in order to improve thereliability of the method, it being determined in the process whether anadditional area appears in the vicinity of an area, so that the twoareas may be assigned to two headlamps or tail lights of a vehicle. Inother words, areas are paired. This makes it possible to obtainindications of twin areas, which may be assigned to lights of motorvehicles, in particular. The classification value of an area isadaptable on the basis of this examination.

According to example embodiments of the present invention, the temporaldevelopment of an area may be tracked on the basis of an image sequence.However, since tracking of the areas is often difficult, the methodaccording to the present invention may also be implemented independentlyof such area tracking, by determining the temporal coherence of theconfidence values. In this case, a confidence value is varied as afunction of its temporal coherence. An accumulation field, inparticular, in which the confidence value is summed up for the pixels ofthe image, is formed for this purpose. In the transition from one imageto the next image, for example, the confidence value for a pixel may bereduced by a fixed value in the accumulation field, and increased by theconfidence value of the corresponding pixel of the following image. Inaddition, in the transition from one image to a following image, thearea in the accumulation field may spread as a function of the expectedmovement of an object assigned to the area. Finally, based on thetemporal development of the accumulation field, it is possible todetermine whether an area will be assigned to a vehicle light, theconfidence values of the accumulation field then being subjected to atemporal hysteresis.

An advantage of determining the temporal coherence of the confidencevalues is that the difficult tracking of a region within an imagesequence is dispensed with. To arrive at a reliable assignment of theregions to vehicle lights, it is sufficient to consider the accumulationfield for only very few full images, so that a very rapid assignment ispossible.

According to example embodiments of the present invention, the trafficregion in a horizontal opening angle of more than 40° is recorded. Theadvantage of using such an opening angle is that the image may beemployed not only for detecting vehicles when it is dark, but that itmay also be utilized by other vehicle applications, especially driverassistance systems. However, such an opening angle makes it is difficultto substantiate vehicle lights at a great distance. According to exampleembodiments of the present invention, the image is therefore recorded bya sensor which has an area that is sensitive only in the particularwavelength range that corresponds to the tail light color of a vehicle,i.e., generally red, and which has another area that detects thebrightness of the incident light, especially in the visible spectrum.The region that detects the brightness of the incident light inparticular does not detect light from the near infrared range.

The region lying in the wavelength range that corresponds only to thecolor of a vehicle tail light takes up 25%, for instance.

The image is recorded by a monochrome camera, in particular.

Further features and aspects of example embodiments of the presentinvention are explained in more detail below with reference to theappended Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a headlamp of the headlamp system accordingto an example embodiment of the present invention;

FIG. 2 schematically shows a headlamp system according to an exampleembodiment of the present invention;

FIG. 3 shows the emission characteristic of the first total lightpattern on a measuring screen, produced by the method according to anexample embodiment of the present invention;

FIG. 4 shows the emission characteristic of the first total lightpattern on a road produced by the method according to an exampleembodiment of the present invention;

FIG. 5 shows the emission characteristic of the second total lightpattern on a measuring screen produced by the method according to anexample embodiment of the present invention;

FIG. 6 shows the emission characteristic of the second total lightpattern on the road produced by the method according to an exampleembodiment of the present invention;

FIG. 7 shows the third total light pattern on the road produced by themethod according to an example embodiment of the present invention;

FIG. 8 schematically shows the structure of the device for detectingother road users;

FIG. 9 shows the method steps for detecting other road users, which areexecuted in the method according to an example embodiment of the presentinvention;

FIG. 10 shows a hysteresis process, which is run through when detectingother road users;

FIG. 11 shows additional possible method steps which are executed whendetecting another road user in the method according to an exampleembodiment of the present invention;

FIG. 12 shows a light pattern in a conventional method in the switchoverfrom the first total light pattern to the second total light pattern;

FIG. 13 shows the light pattern when pivoting from the first total lightpattern to the second total light pattern according to the methodaccording to an example embodiment of the present invention;

FIG. 14 shows an example of the second total light pattern;

FIG. 15 shows the change in the illumination range in the center regionof the second total light pattern according to the method according toan example embodiment of the present invention;

FIGS. 16 and 17 show the change in the second total light pattern in theleft side region when an oncoming vehicle appears, according to anexample embodiment of the present invention;

FIGS. 18 and 19 show the change in the right side region of the secondtotal light pattern during a passing maneuver according to an exampleembodiment of the present invention;

FIG. 20 shows a diagram, from which the illumination range in a sideregion for the second total light pattern results as a function of thehorizontal angle relative to a detected road user according to anexample embodiment of the present invention;

FIG. 21 shows a diagram for illustrating the switchover time in theswitchover from the first total light pattern to the second total lightpattern according to an example embodiment of the present invention;

FIG. 22 shows a flow chart for calculating a delay time;

FIG. 23 shows a flow chart for producing a switchover operation betweenthe second and the third total light patterns according to an exampleembodiment of the present invention.

DETAILED DESCRIPTION

The headlamp system, which is shown schematically in FIG. 2, includestwo projection headlamps 1 and 2 which are set apart from each other andsituated in the front on the right and left side of the vehicle, in a,e.g., conventional manner. One of these projection headlamps 1, 2 isshown in FIG. 1. Projection headlamp 2 situated on the other side hassubstantially the same design.

FIG. 1 shows a section of projection headlamp 1 in a plane that isparallel to the plane defined by the longitudinal vehicle axis andvertical V. In the conventional manner, projection headlamp 1 includes alight source 3, which is surrounded by a reflector 6 implemented asrotation ellipsoid. Reflector 6 thus has two focal points. Light source3 is located in one of the focal points of reflector 6. The lightemitted by light source 3 is reflected by reflector 6 in light emissiondirection L of projection headlamp 1, in the direction of a projectionlens 7. A diaphragm array having planar diaphragms 8 and 9 is disposedat the focal point of projection lens 7 and near the second focal pointof reflector 6. The normals of planar diaphragms 8 and 9 are alignedsubstantially in parallel to light emission direction L. Light source 3,reflector 6, lens 7, and diaphragms 8 and 9 are situated inside ahousing 4, which is closed off by a glass disk 5. The shape of thelight-dark cutoff of the total light pattern of projection headlamp 1 ismodifiable by moving diaphragms 8 and 9 in the vertical and/orhorizontal direction.

The manner in which various total light patterns are able to be producedby moving diaphragms 8 and 9 is described in German Published PatentApplication No. 10 2007 045 150, for instance, which is expresslyincorporated herein in its entirety by reference thereto.

One exemplary embodiment of the headlamp system equipped with a headlamp1, 2 on the right and left side, respectively, as it is shown in FIG. 1,will be described in the following text with reference to FIG. 2.

Right headlamp 1 of the headlamp system is connected to a control unit13, and left headlamp 2 is connected to a control unit 14. Control units13 and 14 control the partial light patterns of headlamps 1 and 2,which, when superimposed, produce a total light pattern.

Control units 13 and 14 control an illumination range regulation forheadlamps 1 and 2, in which headlamps 1 and 2 are pivotable about ahorizontal axis 37 with the aid of actuator 19 or 22. This makes itpossible to pivot light emission direction L of the headlamps in thedirection of arrow A (FIG. 1). Furthermore, control units 13 and 14control actuators 20 and 23, respectively, with whose aid headlamps 1and 2 are pivotable about a vertical axis 38. Using actuators 20 and 23,light emission direction L of headlamp 1 or headlamp 2 is able to bepivoted in the direction of arrow B. Actuators 20 and 23 are part of analready existing cornering light, for example. Finally, control units 13and 14 control the vertical and/or horizontal position of diaphragms 8and 9 of the diaphragm arrays for right and left headlamp 1, 2 with theaid of actuators 21 and 24.

Different total light patterns which are able to be produced byheadlamps 1 and 2 of the headlamp system will be described in thefollowing text with reference to FIGS. 3-7.

First total light pattern 39 produced by the headlamp system is shown inFIG. 3 as an Isolux diagram on a measuring screen, and in FIG. 4, by alight-dark cutoff on a road. Total light pattern 39 is asymmetrical withregard to a center axis 36, which, in the case of a straight road,delimits road lane 26 of vehicle 10 having the headlamp system fromoncoming road lane 27. The illumination range in the region of oncominglane 27 is much lower than the illumination range in the region of lane26 and, for right-hand traffic, also lower than on the right sideadjacent to lane 26. This asymmetry is also apparent from the lightpattern on the measuring screen shown in FIG. 3. An increase 42, whichencloses an angle of 15° with horizontal 35, results on the right sideof first total light pattern 39. In the exemplary embodiment, thecharacteristic of the light-dark cutoff or the light pattern on themeasuring screen corresponds to the requirements of the current EuropeanECE-R 112 standard for a low beam light of a headlamp.

FIG. 5 shows second total light pattern 40 produced by the headlampsystem and the method, in the form of an Isolux diagram on a measuringscreen, and FIG. 6 depicts it as light-dark cutoff on the road. Secondtotal light pattern 40 is a masked permanent high beam. A characteristicof this total light pattern 40 is that it has an illumination range inthe direction of a detected road user 12, i.e., in region M of totallight pattern 40, which is controlled such that it is at least less thanthe distance to detected road user 12 and, in particular, extends toother road user 12. If other road user 12 is a preceding vehicle, thenthe illumination range in region M of total light pattern 40 may extendto the rear bumper of preceding vehicle 12, for example.

A side region S₁, in which the illumination range is greater than theillumination range in region M of total light pattern 40, is formed onat least one side adjacent to center region M in the direction ofdetected road user 12. That is to say, the illumination sweeps aroundroad user 12 in order to provide the driver of vehicle 10 with betterillumination of the traffic area in front of vehicle 10. Theillumination range in side region S₁ may correspond to the illuminationrange in a conventional high beam functionality, for instance. A sideregion S₂, which likewise has a larger illumination range than theillumination range in center region M, is preferably formed also on theother side in second total light pattern 40. The illumination range ofside region S₂, too, may correspond to the illumination range of aconventional high beam functionality, so that total light pattern 40 maycorrespond to a conventional high beam, in which an area of detectedroad user 12 and an area in front of road user 12 in the drivingdirection is cut away in the light pattern. This provides the driver ofvehicle 10 with optimal illumination of the road space, without blindingother road users 12. If yet another road user, such as an oncomingvehicle 11, is detected in the area of illumination of the headlampsystem, the illumination range may furthermore also be controlled in thedirection of this road user 11, such that it extends only to this roaduser 11.

In the case illustrated in FIG. 6, the illumination range in side regionS₂ of second total light pattern 40 is continually adapted to thedistance between own vehicle 10 and oncoming vehicle 11. Furthermore, itis possible to select the width of center region M in such a way thatall detected road users, i.e., vehicles 11 and 12 shown in FIG. 6, forexample, are located within the corridor between side regions S₁ and S₂.But in this case, as well, the illumination range for second side regionS2 is able to be controlled in particular as a function of the positionof an oncoming vehicle 11, as will be explained in the further text.

As described in detail later on, data in connection with other roadusers in front of vehicle 10 in the driving direction are continuouslytransmitted to control unit 16 by an image-processing unit 15 in orderto control the illumination range in center region M and possibly inside regions S₁ and S₂. Depending on the position of other detected roadusers 12 and/or 11, control unit 16 transmits control signals to controlunits 13 and 14 for headlamps 1 and 2. Control units 13 and 14 thereuponcontrol actuators 19 through 21 for right headlamp 1 and actuators 22through 24 for left headlamp 2 such that desired second total lightpattern 40 is generated. In the process the vertical light-dark cutoffis produced by tilting headlamps 1 and 2 about vertical axes 38, on theone hand, and by actuating diaphragms 8 and 9 by actuators 21 and 24 onthe other. In contrast, the horizontal light-dark cutoff in centerregion M, i.e., the illumination range in center region M, is notproduced by shifting diaphragms 8 and 9, but preferably exclusively bythe illumination range control, i.e., by tilting headlamps 1 and 2 abouthorizontal axis 37 with the aid of actuators 19 and 22.

The terms horizontal and vertical used with regard to the light-darkcutoff refer to the light pattern on a measuring screen situatedperpendicularly to light emission direction L. In this case, ahorizontal light-dark cutoff is disposed parallel to horizontal axis 35,which is situated 10 centimeters below the installation height ofheadlamps 1 and 2, with a shield situated at a distance of 10 meters. Avertical light-dark cutoff extends perpendicularly to horizontal axis35.

FIG. 7 shows a third total light pattern 11 as light-dark cutoff on aroad, the pattern being produced by the headlamp system and with the aidof the method. This third total light pattern 41 is also called slidingillumination range. It is characterized by the control of the maximumillumination range of light pattern 41 such that it extends to adetected road user 12 in front of vehicle 10 in the driving direction.This third total light pattern 41 thus ensures an optimal illuminationthat extends to the other detected road user 12, but will not blind thisroad user 12. Side regions S₁ and S₂ of the masked permanent high beamare not provided, however. Third total light pattern 41 is substantiallysymmetrical with regard to a vertical plane extending between headlamps1 and 2 in the direction of light emission direction L. The maximumillumination range in third total light pattern 41 is substantiallyproduced across the entire opening angle, as illustrated in FIG. 7.However, the opening angle is selected such that oncoming vehicles 11 onthe opposite lane will not be blinded when passing vehicle 10 havingthird total light pattern 41. The control of the maximum illuminationrange of third total light pattern 41 is implemented by diaphragms 8 and9, i.e., it differs from the control of the illumination range in centerregion M of second total light pattern 40.

Furthermore, a device for detecting a road user in the driving directionof the vehicle, i.e., usually in the direction of light emission L ofheadlamps 1, 2, is provided. This detection device, as shown in FIG. 2,may be a camera 18 having a connected image-processing unit 15, whichdetects the lights of vehicles 11, 12 driving ahead or approaching fromthe opposite direction. The direction of these lights both in ahorizontal and a vertical direction are detectable with the aid ofimage-processing unit 15. Image-processing unit 15 analyzes the scenerecorded by the forward-facing camera. In this scene the position of thelights of vehicles 11, 12 driving ahead and approaching from theopposite direction is detected. Based on the horizontal distance of twoheadlamps or tail lights of another vehicle 11, 12, the image processingis additionally able to infer the width of the vehicle. Light sources ofother road users are able to be recorded as well. Finally, it ispossible to detect light sources which indicate street lights or alocality. Street lights are usually able to be distinguished fromvehicle lights by the position in the camera image or by the intensity,which is frequency-modulated by the grid. The opening angle of thecamera preferably corresponds to the opening angle of the headlampsystem.

The detection device 15 may be implemented as laser or radar sensor, bywhich the distance of objects in the direction of light emissiondirection L is able to be measured. In so doing, road users that are notilluminated or insufficiently illuminated, in particular, such aspedestrians or possibly also bicycle riders are detectable as well. Inaddition, it is possible to use the distance measurement to selectivelydetect road users located within the glare boundaries of a lightpattern. Finally, an excellent classification of vehicles or road usersmay be implemented via the measurement of distance, speed and movementdirection of road users, so that a faulty control of the headlamp systemis avoided. The vertical angle, i.e., the distance from the own vehicle,may be calculated from the distance of the object, the angle beingusable as control quantity for the headlamp system.

In addition, utilizing the distance measurement of the laser or radarsensor, it is possible to distinguish between a moving vehicle andstationary objects by a speed detection. Moreover, using a scanninglaser distance meter, the width of the detected objects is able to bemeasured, so that the type of objects, i.e., whether they involve a roaduser, a motor vehicle, a bicycle rider or a guidepost, may be inferredwith greater certainty.

The laser or radar sensor may also be combined with a camera in order toincrease the detection reliability, especially with regard to detectingthe vertical position of the road user. Since cameras, laser and radarsensors are increasingly used in vehicles equipped with driverassistance systems, this sensor technology may be used for controllingthe headlamp system as well without creating additional expense.

An arrangement of the device for detecting a road user will be describedin detail in the following text with reference to FIGS. 8 through 11:

In this case the detection device includes a sensor, which records animage of a road section in the visible spectral range. The sensor, forinstance, may be situated behind the windshield in the driving directionand be aligned with the road in front of the vehicle. The sensor is amonocular image recording system, which is able to detect, in real time,light sources located in front of the own vehicle at a distance of morethan 600 m. Headlamps of another vehicle at a distance of 600 m and taillights of another vehicle at a distance of more than 400 m, inparticular, are detectable.

The sensor may be integrated into camera 18 and utilized not only forimage recordings which are used for the control of headlamps 1, 2 of thevehicle once the images have been processed. Instead, the imagerecordings of the sensor are also able to be used for other driverassistance systems such as a lane track assistance and road signdetection system. This multiple use of the sensor lowers the costs inthe production of the vehicle.

In darkness, vehicles are usually detected based on the light emissionof their headlamps or the light emission of their tail lights. It isapparent that simply forming a threshold value for the luminousintensity occurring in the recorded image does not lead to a reliablevehicle detection. The light emitted by the vehicle itself, which isreflected at different objects located within the road section in frontof the vehicle, back to the vehicle, makes it difficult to distinguishbetween such reflections of the own light and other vehicles for mediumand large distances. Both the sensor and the subsequent image processingof the image recorded by the sensor must therefore be adapted to thisproblematic situation.

First of all, to allow an effective differentiation between a headlampand a tail light, the sensor has an area that is sensitive only in thewavelength range that corresponds to the color of the tail light of avehicle, in other words, this sensor region is sensitive to red lightexclusively. However, since in contrast to monochromatic sensors, i.e.,sensors which measure the brightness or the gray-scale value, the sensoralso includes a region which detects the brightness in the visiblespectral range. The sensor region for the brightness uses 75% of thepixels in this sensor, and the region for red light, 25% of the imagepixels. If such a sensor is used, it is possible to record images thatare also usable by other applications.

The horizontal opening angle of the sensor is greater than 40°, forexample. Such an opening angle makes it difficult to detect tail lightsat a great distance. For example, a tail light having a size of 10 cm×10cm is imaged by less than one pixel of the sensor at a distance of morethan 100 m. On the other hand, the light emitted by the tail light formsa larger cone, so that a tail light at an approximate distance of 400 mis still imaged in an area of approximately 4 to 10 pixels. However, inorder to obtain color information from the image provided by the sensor,the preceding filter system having one red and three pixels withoutcolor filter, a so-called Bayer matrix, is used. The sensor includes 2×2blocks having a single sector that is sensitive in the red spectralrange, and three conventional monochrome detectors, which have a highersensitivity than color-sensitive detectors, but which also detect lightin the red spectral range. Such a sensor makes it possible todistinguish red light sources from white light sources, whilesimultaneously providing high sensitivity for the pixels without colorfilter, however. It is pointed out that the sensor is insensitive in thenear-infrared range and works with 10 bits per pixel using a logarithmiccurve, which essentially prevents completely saturated pixels, in whichinformation is lost.

The sensor is connected to an image-processing unit 15. Image processingunit 15 analyzes the image recorded by the sensor such that light imageareas of the recorded image are able to be assigned to vehicles in thetraffic environment of the own vehicle. The image processing takes intoaccount that there are considerable differences in the bright areasrecorded by the sensor for vehicles in the vicinity of the own vehicleand vehicles at a great distance. Corresponding differences also resultfor light areas stemming from headlamps and those stemming from taillights. The intensity of bright areas caused by headlamps is greater andwhite, whereas light areas caused by tail lights have a lower intensityand are more red. Furthermore, the image processing takes into accountthat the device must respond more quickly for vehicles that are nearerto the own vehicle, than for vehicles that are at a greater distancefrom the own vehicle.

The individual components of image-processing unit 15 and the steps fordetecting another road user are explained in the following text withreference to FIGS. 8 through 10.

As described above, in step 100, an image of the traffic region in thevisible spectrum in front of own vehicle 10 is first recorded with theaid of the sensor.

In step 110, extraction unit 31 is employed to determine which cohesiveareas of the image have a brightness that exceeds a specific thresholdvalue. These image areas are extracted. It must then be determined forthese image areas whether they are to be assigned to another vehicle orto another object that is not a vehicle. Since the extraction is basedon the formation of a simple threshold value, image-processing unit 15is able to perform it very rapidly, i.e., preferably in real time. Thecohesive areas of the image whose brightness exceeds the threshold valueare also called blobs.

The following steps 120 through 140 are then executed for each area:

In step 120, the areas are classified by a classifier 32. They are alsoassigned a classification value. To do so, different characteristics ofthe area are determined to begin with. Especially important among thesecharacteristics are the maximum gray-scale value of the area and the redcomponent of the area. Furthermore, in particular the followingadditional potentially useful characteristics of the area are determinedin the method and used in the classification: (1) the binary values ofthe area, especially the surface area, the center of mass, thedimensions, the border and/or the main axes; (2) the intensity or thegray-scale value stemming only from the monochrome pixels, in particularthe maximum, the median value, the standard deviation, the position ofthe maximum within the area, the distribution of the histogram, and/orthe magnitude of the medium gradient; (3) the same characteristics, butfor red pixels only; and (4) characteristics from which colorinformation is obtainable by different comparisons of monochrome and redpixels, e.g., the ratio between the median value of the monochrome leveland the median value of the red level.

Since it is usually impossible to reliably infer a vehicle as the lightsource based on a single characteristic or based on the afore-describedcharacteristics, the characteristics of the areas are subjected to alearning algorithm. Using the learning algorithm, a classification isultimately obtained with classification values for the areas andfinally, discrete, weighted classification values for the areas. TheReal-AdaBoost algorithm as described in R. Schapire and Y. Singer,“Improved boosting using confidence-rated predictions” in MachineLearning, vol. 37, No. 3, pages 297-336, 1999, is used as learningalgorithm. Using this learning algorithm, differences in thecharacteristics of vehicle lights are taken into account in order tosubdivide the different areas from the outset: Small areas and areasthat are not small have a different appearance; in addition, areasstemming from headlamps differ from those stemming from tail lights. Onthe basis of this approach, the areas have been subdivided into fourbasic classes:

-   -   C_(h,s): for the detection of oncoming vehicles 11, which are        located at a medium to large distance from the own vehicle;    -   C_(h,ns): for the detection of oncoming vehicles 11, which are        situated at distances in the vicinity of the own vehicle, up to        a medium distance;    -   C_(f,s): for the detection of vehicles 12 driving ahead at a        medium to large distance;    -   C_(t,ns): for the detection of vehicles 12 driving ahead, which        are located near the own vehicle, up to a medium distance.

According to the axiom that it is better to produce a wrong assignmentto a vehicle than to miss a correct assignment, the maximum value of thefour output signals of the learning algorithm is chosen once the areashave been subdivided into the classes.

In step 130, a first decision as to whether or not an area is to beassigned to a vehicle is able to be made already on the basis of thisbasic classification. If such a rough assignment is possible, the methodcontinues with step 140. If such a rough assignment is not possible, themethod continues with step 150, which will be discussed later in thetext.

Even if the rough assignment to a vehicle is able to be made in step130, it has become clear that this rough assignment does not lead to a100% detection of vehicles. Furthermore, it cannot be ruled out that areflection of the own light or the light emission of another object istaken for a vehicle light.

For this reason, in the method a confidence value is determined for eacharea in step 140 by a confidence unit 33, the confidence valueconstituting a measure for the similarity between the image area and avehicle light. This confidence value may be calculated from a previouslydetermined classification value of the area and a physical quantityassigned to the area. However, discrete, weighted classification valuesfor the areas are preferably obtained from the classification values bythe learning algorithm.

The classification value is derived from the afore-describedReal-AdaBoost algorithm based on examples from areas that areattributable to vehicular light sources, and corresponding contrastingexamples. The result is a classification value c; here, positiveclassification values indicate that an area resembles a vehicle light,and negative classification values point to the opposite. Classificationvalues c are then discretized into corresponding weighted classificationvalues, the weightings being allocated in the following manner:

$\omega = \{ \begin{matrix}\omega_{+} & {if} & {c \geq t_{+}} & {applies} \\\omega_{0} & {if} & {t_{0} \leq c \geq t_{+}} & {applies} \\\omega_{-} & {if} & {t_{-} \leq c < t_{0}} & {applies} \\0 & {if} & {c < t_{-}} & {applies}\end{matrix} $

t₊, t₀ and t_ being threshold values which are set for each class, andω₊, ω₀ and ω_ being corresponding weightings which are defined for eachclass. Above t₊, one can be sure that an area is assignable to avehicle, and below t, one can be sure that this area cannot be assignedto any vehicle. The range from t_ to t₊ is considered an uncertainoutput of the classification; from t_ to t₀ it is assumed that the areamore readily resembles a light source that does not belong to anothervehicle, whereas in the range from t₀ to t_, it is assumed that theareas are more similar to a vehicle light. The following table shows anexample for the threshold values that are used:

In order to obtain no incorrectly classified areas headlamp tail lightclassification classification small not small small not small (t, ω)₊(1, 1)   (1, 1′5) (1, 0′5) (1, 1) (t, ω)₀   (0, 0′5) (0, 1)  (0, 0′25)  (0, 0′25) (t, ω)⁻ (−2, 0)  (−2, 0)  (−2, 0)   (−2, 0)  correctlyclassified 78%/75% 97%/97% 60%/65% 94%/93% (vehicles/no vehicles) nodefinite decision 22%/25% 3%/3% 40%/35% 6%/7% (vehicle/no vehicle)

At these threshold values for the above equation, no areas areclassified incorrectly. In addition, the correct classification forareas that are not small is above 90%.

Next, a confidence value v is calculated for each area based on theweighted classification values. If it is assumed that g is the maximumgray-scale value of a given area, normalized across the maximallypossible gray-scale value for an area, the confidence value is definedin the following manner:

v=ω×g,

ω being the weighted classification value assigned to the area. Theconfidence value thus is obtained from the certainty in theclassification multiplied by the certainty of a physical quantity, inthis case, the maximum gray-scale value of the area, in particular themaximum gray-scale value of a given area, normalized across themaximally possible gray-scale value. The maximum gray-scale valuetherefore influences both the weighted classification value and thephysical quantity. However, when obtaining the weighted classificationvalues, threshold values learned by an algorithm via differentcharacteristics of the gray-scale value are used, whereas thecalculation of the physical quantity uses the gray-scale value directly.

In the afore-mentioned calculation of the confidence value, it is takeninto account that vehicles which are closer to the own vehicle generatebrighter areas in the image recorded by the sensor than vehicles thatare at a greater distance. As a result, areas classified as belonging toa vehicle, i.e., to a vehicle in the vicinity of the own vehicle, willhave a higher confidence value. If a vehicle is farther away, then theassociated area of the image of the sensor may indeed have a highconfidence value, but it will be a lower value than that of the areaassigned to a closer vehicle. A bright region caused by a reflection isgoing to have a lower confidence value if classified correctly, and thisconfidence value will be even lower for areas that are caused byreflections stemming from objects at a large distance.

If the result of step 130 has shown that it is impossible to establishthe basic classification for a vehicle, then additional information willbe utilized for the classification in step 150. Especially theenvironment of the area can be examined for this purpose. In thisexamination it may be determined whether another area appears in thevicinity of an area, so that the two areas are assignable to twoheadlamps or tail lights of another vehicle. In particular for areas forwhich the result in the basic classification in step 120 had been thatt_≦c≦t₊, for example, such an examination of the environment may beundertaken. If the environment examination finds a pair of lights, thenthis is an indication of a twin area caused by the right and leftheadlamp or the right and left tail light of a vehicle. Of course, thisexamination will have a positive result only for vehicles having twoheadlamps or tail lights, and not for motor cycles and similar vehicles.

When examining the environment, a window of a size that is proportionalto the outline of the area is placed in the left and right side of thearea for each area. On the left and right side within each window, asearch is conducted for other areas whose center of mass lies within oneof the windows. In the event that such a potential twin area has beenfound, a few of the afore-described characteristics are compared to eachother. Each comparison includes the calculation of a ratio, e.g., theratio of the maximum gray-scale value of the two areas. These ratiosform a set of characteristics, which is able to be linked to othercharacteristics, such as the distance of the centers of mass, theabsolute value of the maximum gray-scale value, etc. These values form aset of characteristics, which is used for the afore-describedReal-AdaBoost algorithm for the classification. The new classificationresult of the learning algorithm is utilized for modifying weightedclassification value ω obtained in the afore-described classification.The following rule is used for this purpose: If a negative value (notwin areas) results from the pairing classification, then weightedclassification value ω will not be modified; otherwise, this weightedclassification value is set to a higher value, i.e., ω_ becomes ω₀ or ω₀becomes ω₊. These weighted classification values are then used as thebasis in the further method steps.

Once the confidence values for the areas have been determined in step140, the temporal coherence of the confidence values is determined instep 160, for which purpose a temporal coherence analysis is performed.It is pointed out that the confidence values for the subsequent temporalcoherence analysis may also be obtained in a manner that differs fromthe one described above. On the other hand, the temporal coherenceanalysis may also be omitted if the weighted confidence values have beendetermined as described above.

One possibility for a coherence analysis is based on target tracking,i.e., tracking the temporal change of the areas in the image recorded bythe sensor. Such target tracking is optionally carried out. However, itis difficult to implement and not without errors. For that reason, acoherence analysis that does no require target tracking may beperformed.

In the temporal coherence analysis, an accumulation field A is formed inorder to determine whether the assigned confidence values are temporallycoherent. Accumulation field A has the same dimensions as the originalimage. When updating the accumulation field, the following steps areexecuted:

-   -   1. The values of accumulation field A range from 0 up to a given        value M_(A), beginning with A=0.    -   2. When a new image k has been obtained:        -   (a) A is reduced. A decay of the accumulation is implemented            by the arithmetic step A=max(0,A−d), where d is a fixed            number which defines the decay component. If one begins with            M_(A), then M_(A)/d steps are required to obtain 0. It is            possible that d assumes different values from two            possibilities in different cells of accumulation field A and            by a hysteresis method.        -   (b) Spread of A. The values of each cell are spread            according to the expected movement of the targets in order            to combine confidence values that stem from the same target            from image to image.        -   (c) Increase of A. Assuming that A_(i) ^((k)) is a            coordinate set which forms area i detected in current image            k, and v_(i) ^((k)) is the corresponding confidence value,            the following updating formula is used:            AAi^((k))=min(A^((k−1))Ai+v_(i) ^((k)), M_(A)), A_(A)i            representing the cell of A whose coordinates correspond to            A_(i).

In the spreading step, a type of dilation is implemented, which issimilar to the mathematical morphology of the gray-scale values, butwhose structuring element differs in different accumulation cells. Thedifference is caused by the expected movement of the various targets inthe image space. Targets in the vicinity of the horizon remainrelatively static from image to image, whereas the position of closertargets varies more strongly. Furthermore, oncoming vehicles move fasterin the direction of the lower edge of the image, whereas vehiclesdriving ahead do not exhibit such behavior. Therefore, the accumulationfield is used especially for areas which are more similar to those thatare caused by headlamps, than those that stem from tail lights, andanother field is used for the remaining areas. This other field isselected according to the classification if it had a higher outputduring the basic classification.

The areas for image k are finally classified as vehicle lights or novehicle lights in accordance with a hysteresis criterion related to thecorresponding positions of the accumulation field. This means that eachaccumulation field has an assigned status field S of the samedimensions. As illustrated in FIG. 10, the hysteresis is thenimplemented in the following manner:

-   -   If cell A_(i,j) is zero, then the corresponding value of status        field S_(i,j) is set to the value INCORRECT. The next decay        component for A_(i,j) is d=d_(f), d_(f) being a fixed number;    -   if A_(i,j) M_(A)/2, then S_(i,j) is set to the value TRUE and        d=d_(t), where d_(t) is a fixed value;    -   if 0<A_(i,j)<M_(A)/2, then S_(i,j) remains unchanged, and there        will also be no resulting associated decay of A_(i,j).

Consequently, the logical OR operation is used for SAi^((k)) for a givenarea i with A_(i) ^((k)) in image k, in order to finally assign theareas to a vehicle or not to assign them to a vehicle.

During the temporal coherence analysis, the maximum value for thehysteresis criterion is set to M_(A)=2, so that the hysteresis assignedto a cell of the accumulation field assumes the TRUE state aboveM_(A)/2=1 and does not reach the status INCORRECT before the zero valuehas been attained again, as illustrated in FIG. 10. The following valuesare selected for the decay control: (d_(t), d_(f))=(45, 15) images,which means that when a vehicle disappears, the system continues toilluminate the new free area for only another approximately two seconds.The same values are selected for the accumulation field of the areasthat resemble headlamps and for the areas that resemble tail lights.

As explained, an accumulation field in which the confidence value issummed up for the pixels of the image thus is formed for determining thetemporal coherence. In a transition from one image to a following image,the confidence value for a pixel is reduced by a fixed value andincreased by the confidence value of the corresponding pixel of thefollowing image. In the process, in the transition from one image to afollowing image, the area may spread as a function of the expectedmovement of an object assigned to the area. The final decision as towhether an area will be assigned to a vehicle light is made based on thetemporal development of the accumulation field, the confidence values ofthe accumulation field being subjected to a temporal hysteresis. Thisfinal assignment is made by means of assignment unit 34 in step 170.

A method for detecting other road users will be explained in thefollowing text on the basis of FIG. 11.

Similar to the first arrangement, a sensor for recording an image of atraffic region in the visible spectrum and an image-processing device 15are utilized. The detection of the road users, e.g., the vehicles, takesplace on the basis of the vehicle lights, i.e., based on the lightemission of the front headlamps in the case of oncoming vehicles 11 andbased on the light emission of the tail lights for preceding vehicles12.

In step 180, similar to step 100 of the first development, an image ofthe traffic area in front of own vehicle 10 is recorded. In step 190,similar to step 110 of the method of the first development, cohesiveareas having a brightness that exceeds a threshold value are extracted.Thus, a search takes place for cohesive bright pixels in the imageproduced by the sensor, which have a predefined intensity and possiblyexceed a specified magnitude in addition. Such image areas may belong tolight sources of another vehicle, but also to other light sources orreflections of the light emission of the own vehicle. The resultobtained from step 190 is a binary image, in which cohesive areas havingbright pixels are defined by a border. Furthermore, similar to the firstdevelopment, characteristics such as the size, the brightness, coloretc. are determined for the areas. If the analysis of an individualimage shows that an area is most likely assignable to a vehicle light,then the method may continue directly with step 250 for these particularareas. Furthermore, it is possible to classify the areas based on thecharacteristics of the areas in step 240. Finally, still furtherinformation may be obtained in connection with the areas, as will bedescribed in the following text:

In step 200, an environment analysis of the areas is performed for eacharea. This environment analysis, for example, may include the pairformation based on twin areas described in the first development, inwhich two bright areas are assigned to a headlamp pair or a tail lightpair in each case. The result of the environment analysis in step 200 isprocessed further in a step 240.

Another optional processing step concerns the tracking of one ormultiple area(s) in an image sequence and determining the movement ofthe area(s). To make it easier to find an area in the image sequenceagain, a global movement estimate is implemented for this purpose instep 230. The own movement of vehicle 10 is calculated and taken intoaccount when tracking the areas. In step 230, the global movement isable to be determined based on the correlation of the movement ofmultiple objects in the image. However, it may also be determined viavalues that are made available by the odometer system in the vehicle, orby other sensors in the vehicle such as acceleration sensors, forexample. A combination of both approaches is possible as well.Image-processing unit 15 is linkable to vehicle bus 17 for this purpose,for instance via control unit 16. Taking the global movement of thevehicle determined in step 230 into account, the movement of theindividual areas in the image sequence is determined in step 220.

If image-processing unit 15 tracks the areas across a plurality ofimages, it is moreover possible in step 210 to stabilize the internalcharacteristics of the areas that may fluctuate slightly from image toimage, across a plurality of images. For this purpose, thecharacteristics of the areas are averaged over time across a pluralityof images in step 210. This method step is especially advantageous fordetermining the color of a very small area. In the case of a small imagearea, the light impinges on only very few pixels of the sensor. In acolor image sensor, the individual pixels are sensitive to only onecolor, usually to red, green or blue. A color determination is possibleonly if the area impinges on a sufficient number of pixels of all colorcomponents. If the size of the area is insufficient, then the pixels ofthe area determined for a plurality of consecutive images may beutilized for this purpose in step 210.

The data obtained in steps 190, 200, 210 and/or 220 are processedfurther in step 240. As described in the first example embodiment, theareas are classified as a function of their size as well as theadditional characteristics obtained in the preceding steps; furthermore,a confidence value, especially the weighted confidence value, isdetermined for the areas, as described previously. The higher theconfidence value, the higher the probability that the area may beassigned to a vehicle light, i.e., the headlamp of an oncoming vehicle11, or the tail light of a preceding vehicle 12.

If the monitoring of an area in an image is insufficient for anunequivocal classification, the confidence value is added up for eacharea across a plurality of images in step 260. The movement of eacharea, determined in step 220, is taken into account. If an area is ableto be monitored across a plurality of images, a new confidence value isdetermined by summing up or reducing the confidence values of the area.

In parallel or alternatively, the confidence value for each pixel isable to be added up or reduced. This does not require tracking of theareas. In step 250, the image areas, i.e., the pixels within the borderof a specific area that has been determined by the afore-mentionedsteps, are provided with the confidence value of this area. In asubsequent image, a specific value, as explained in the firstdevelopment, is automatically deducted from the confidence value of thearea, so that the confidence value drops to zero over time in areaswhich no longer include any bright areas in the following images. At thesame time, the accumulated confidence of the area lying underneath isadded to the confidence value of an area for each subsequent image. Thisresults in a new confidence value, which not only contains the currentconfidence of the area, but, via two-dimensional accumulation, also theconfidences of areas in this image area that occurred just previously.Furthermore, in step 250, this two-dimensional confidence field of anarea may be enlarged from image to image in the decay. The propagationdirection in the enlargement of this confidence field is adaptable tothe expected object movement or to the expected movement of own vehicle10. This ensures that, despite the movement of an area, the area isstill based on confidence values that were generated by the same area inthe preceding image.

If the classification generated in step 240 ultimately produces aconfidence value that allows an unequivocal decision as to whether ornot a particular region is assignable to a vehicle light, then theresult of step 240 may also be processed further in a direct manner. Instep 270, the confidence values determined in this manner in steps 240,250 and 260 are combined and a final decision is made as to whether thisarea is a relevant object, i.e., whether the brightness in this areacomes from a light source of another vehicle, or whether this is not thecase.

Finally, in step 280, areas that are able to be assigned to othervehicles 11, 12 are output together with the appropriate coordinates inrelation to own vehicle 10. Especially the angular positions of thedetected preceding or oncoming vehicles 11, 12 relative to own vehicle10 result from these coordinates.

It is pointed out that steps 200, 210 and 220 may also be omittedaltogether as a function of the result of step 190; it is also possiblethat only a single step or individual ones of these steps is/areexecuted. In addition, steps 250 and 260 may be executed in parallel oras an alternative. Finally, they may also be completely omitteddepending on the result of step 240.

Ultimately, it is possible to utilize the hysteresis, which has beenexplained with reference to the first example embodiment. If aconfidence value is exceeded, then the area is classified as a relevantobject. If a lower value is not attained, then the area will no longerbe classified as relevant object. The accumulation of the confidencevalues in processing steps 250 and 260, or the accumulation inprocessing step 210 is cut off at a set maximum value. This ensures thata drop below the lower hysteresis threshold will be achieved again insufficient time.

Using camera 18, which includes the afore-described sensor, andimage-processing unit 15, it is therefore detected whether another roaduser, in particular an illuminated road user, is located in front of ownvehicle 10 in the driving direction. In addition, the position of such aroad user in relation to the own vehicle is determined. The data inconnection with a detected other road user are transmitted toimage-processing unit 15 by control unit 16.

In addition, control unit 16 is connected to a vehicle bus 17, via whichadditional data detected in the vehicle are able to be transmitted tocontrol unit 16. For instance, geographical data from a navigationsystem 28 are transmittable to control unit 16 by way of vehicle bus 17.Navigation system 28 is able to determine the current position ofvehicle 10 by means of a receiving sensor, which may be implemented asGPS (Global Positioning System) receiver 29, for example.

The headlamp system may furthermore include a device 25 for detectingthe driving behavior of vehicle 10. Device 25, for instance, may becoupled to an internal clock and a speedometer of the vehicle viavehicle bus 17, and determine the acceleration of vehicle 10 based onthe transmitted speed using the time signal from the internal clock. Viathe temporal development of the magnitude of the acceleration or thesize of the absolute value of the acceleration, device 25 is able todetermine a driving dynamics characteristic and assign it to a specificclass for the driving behavior. Furthermore, an input signal of thedriver specifying the driving behavior, for instance, may be transmittedto device 25. Finally, device 25 is also able to determine the drivingbehavior as a function of a driver type. For this purpose device 25 maybe coupled to a device for determining the person of the driver, viavehicle bus 17. Historical data in connection with this driver isstorable in device 25, so that device 25 is able to assign a particulardriver type, which determines the driving behavior, to the currentdriver. The driving behavior determined by device 25 is transmitted to atimer 27. Timer 27 determines a time interval ΔT for the transition fromone total light pattern to another total light pattern, as a function ofthe determined driving behavior. Timer 27 transmits determined timeinterval ΔT to control unit 16, which processes it further.

In addition, control unit 16 is connected to a delay unit 26. Delay unit26 determines a delay time by which a switchover between two total lightpatterns or between two illumination states for the illumination rangeis delayed. The manner in which the delay time is determined by delayunit 26 will be described in greater detail at a later point.

In the following text, it is described in which manner theafore-described headlamp system may be controlled or regulated.

The manner in which a switch takes place from first total light pattern39 to second total light pattern 40 will be elucidated with reference toFIGS. 12 and 13. Vehicle 10 is traveling on a single lane 26, forexample. The headlamp system of vehicle 10 produces first total lightpattern 39. Using camera 18 and image-processing unit 15, a controlsignal is transmitted to control unit 16 due to other detected roadusers 11 and 12, to the effect that a switch should take place fromfirst total light pattern 39 to the masked permanent high beam of secondtotal light pattern 40.

In the transition from first total light pattern 39 to second totallight pattern 40, control unit 14 of left headlamp 2 controls actuator23 such that light emission direction L of second headlamp 2 is pivotedhorizontally toward the outside in the direction of the oncoming lane,away from light emission direction L of first headlamp 1. Since in firsttotal light pattern 39, the greater illumination range in the rightregion of total light pattern 39 is also produced by the light emissionof second, left headlamp 2, among others, the problem arises that otherroad users 11 and 12 would be blinded when left headlamp 2 is pivotedabout vertical axis 38. This situation is schematically illustrated inFIG. 12.

To avoid such blinding of other road users 11 and 12 during theswitchover from first total light pattern 39 to second total lightpattern 40, the method initially reduces the illumination range of leftheadlamp 2 (in right-hand traffic) on the right side of center axis 36between lanes 26 and 27, at least to such an extent that it is less thanthe distance to a detected road user 11 or 12. Only then will secondtotal light pattern 40 be produced by increasing the illumination rangein the left side region adjacent to detected road users 11 and 12, sothat a corridor is created which has a lower illumination range for oneof the road users 11 or 12 or for both road users 11 and 12. FIG. 13illustrates the switchover from first total light pattern 39 to secondtotal light pattern 40. It should be understood that other road usersare not blinded during the switchover either.

A corresponding approach is used if the reverse takes place, i.e. aswitch from second total light pattern 40 back to first total lightpattern 39, in that first, a left side region S2 of second total lightpattern 40 is blanked out, so that the illumination range in this regioncorresponds to the illumination range in center region M; left headlamp2 is then pivoted about vertical axis 38, back into the position forfirst total light pattern 39, and only then, will the asymmetrical lightpattern that is characteristic of first total light pattern 39 beproduced by left headlamp 2 as well.

If a so-called city-light functionality is able to be produced by theheadlamp system, in which the asymmetry of first light pattern 39 iscanceled and a maximum illumination range is provided which is so lowthat other road users are not blinded, it is also possible to firstswitch to the city-light functionality in the switchover from firsttotal light pattern 39 to second total light pattern 40, whereupon leftheadlamp 2 and possibly also right headlamp 1 is/are pivoted aboutvertical axis 38 in the outward direction in order to finally producethe masked permanent high beam of second total light pattern 40.

The control of the illumination range in center region M in second totallight pattern 40 will be explained with reference to FIGS. 14 and 15. Inthis case, in contrast to the example shown in FIG. 10, a corridorhaving reduced illumination range 43 is formed in a center region M insecond total light pattern 40, in which both a preceding vehicle 12 andoncoming vehicles 11 a, 11 b are situated. A second total light pattern40 adapted in this manner is able to be produced by a control signalfrom image-processing unit 15 in the event that increased trafficdensity is encountered, in which case a permanent control of theillumination range in left side region S2 would be disadvantageous.

Side regions S₁ and S₂ of adapted total second light pattern 40 shown inFIGS. 14 and 15 are produced, for instance, by pivoting the twoheadlamps 1 and 2 about vertical axis 38 in their light emissiondirection L, farther away from each other. The inner vertical light-darkcutoffs in the corridor for vehicles 11 and 12 are produced by shiftingdiaphragms 8 and 9 with the aid of actuators 21 and 24. However, thehorizontal light-dark cutoff in center region M, i.e., illuminationrange 43 in this center region M, is produced exclusively by theillumination range control, in that headlamps 1 and 2 are pivoted abouthorizontal axis 37 by means of actuators 19 and 22. The control isimplemented such that light-dark cutoff 43 is adapted to the distance todetected road users 11 and 12. For example, starting from the trafficsituation shown in FIG. 14, if oncoming vehicle 11 a has passed by, theillumination range to preceding vehicle 12 is adjusted to value 44 shownin FIG. 15. This type of control of illumination range 43 in centerregion M of the second total light pattern is also especiallyadvantageous when driving uphill and downhill.

FIGS. 16 through 19 show a further refinement of the control of secondtotal light pattern 40. Similar to the example discussed with referenceto FIGS. 12 and 13, the illumination range in center region M iscontrolled in such a way that it extends to next detected road user 11,12. The opening angle for center region M thus is selected in such a waythat it detects the direction of all detected road users 11 and 12 infront of own vehicle 10 in the driving direction. On the right side,adjacent to center region M, a side region S₁ having a greaterillumination range is formed. A second side region S2 having anincreased illumination range is also formed on the left side adjacent tocenter region M.

In the situation shown in FIG. 16, in which a preceding vehicle 12 andan oncoming vehicle 11 a have been detected, the illumination range inleft side region S2 is at a maximum, i.e., L_(max). If oncoming vehicle11 a continues to approach vehicle 10 having the headlamp system, theproblem arises that the driver of vehicle 11 a would be blinded by leftside region S2 if center region M were formed using the smallest openingangle possible. If oncoming vehicle 11 a comes closer to own vehicle 10,the opening angle for center region M becomes larger. However, when anoncoming vehicle 11 a reaches the left vertical light-dark cutoff toside region S2, left lateral range S2 must be switched off, i.e., theillumination range of left side region S2 must be lowered to theillumination range of center region M in order not to blind passingvehicle 11 a. The closer vehicle 11 a is to own vehicle 10, the higherthe speed at which the illumination range of left side region S2 must belowered to avoid the blinding, since the relative angular velocity ofpassing vehicle 11 a becomes very high and thus very little time remainsfor lowering the illumination range in left side region S2.

In order to avoid the danger of blinding a passing vehicle 11 a, themethod controls illumination range LW₂ in the direction of left sideregion S₂ of the second total light pattern as a function of horizontalangle Φ between driving direction FR of vehicle 10 and the connectingline from vehicle 10 to oncoming vehicle 11 a. Illumination range LW₂ inleft side region S₂ of second total light pattern 40 is lowered earlyenough to avoid an abrupt change in second total light pattern 40 whenan oncoming vehicle 11 a passes own vehicle 10. The illumination rangeof right side region S₁ may remain unchanged in such a case. The innervertical light-dark cutoff of second side region S₂ is controlled as afunction of the position of preceding vehicle 12 in this case.

The control of the second total light pattern during a passing maneuveris illustrated with reference to FIGS. 18 and 19. In front of ownvehicle 10 is a preceding vehicle 12, in whose direction theillumination range is less than the distance to preceding vehicle 12.During a passing maneuver, vehicle 10 drives onto the oncoming lane andapproaches vehicle 12 driving ahead. In this case, illumination rangeLW₁ in right side region S₁ of total light pattern 40 is controlled as afunction of horizontal angle Φ between the driving direction of vehicle10 and the connecting line from vehicle 10 to preceding vehicle 12. Thecloser vehicle 10 comes to preceding vehicle 12, the more illuminationrange LW₁ is reduced in right side region S₁. The control for reducingright side region S₁ may take place automatically on the basis of thedata transmitted by image-processing unit 15. However, the control mayalso be induced by setting the turn signal indicator in the direction ofthe oncoming lane, possibly in connection with data for the accelerationof vehicle 10.

During a passing maneuver, vehicle 10 drives onto the oncoming lane andapproaches vehicle 12 driving ahead. In this case, illumination rangeLW₁ in right side region S₁ of second total light pattern 40 iscontrolled as a function of horizontal angle Φ between the drivingdirection of vehicle 10 and the connecting line from vehicle 10 topreceding vehicle 12. The closer vehicle 10 comes to preceding vehicle12, the more illumination range LW₁ is reduced in right side region S₁.The control for reducing right side region S₁ may take placeautomatically on the basis of the data transmitted by image-processingunit 15. However, the control may also be induced by setting the turnsignal indicator in the direction of the oncoming lane, possibly inconjunction with data for the acceleration of vehicle 10.

FIG. 20 shows an example for a functional correlation betweenillumination range LW, i.e., LW₁ and LW₂, and horizontal angle Φ toanother road user 11 and 12, respectively. In this example, horizontalangle Φ is positive both in the direction of an oncoming vehicle 11 andin the direction of a preceding vehicle 12 being passed. Up to an angleof 0.5 degrees, illumination range LW in side region S₁ or S₂ is at amaximum, i.e., it corresponds to illumination range L_(max). At largerhorizontal angles Φ, illumination range LW is reduced in linear fashion,until it assumes a minimum value starting at 4.5 degrees, at which otherroad users are no longer blinded. In this context, the illuminationrange is determined as follows:

LW=L_(max) for Φ<0.5 deg

LW=L _(max)(−0.25·Φ+1.125) for 0.5 deg≦Φ≦4.5 deg,

LW=0 for Φ>4.5 deg

The increase in the curve illustrated in FIG. 20 may also be varied. Forexample, it may be increased up to 0.4⁻¹ degrees or lowered down to0.16⁻¹ degrees. The limit angles for the decrease in the illuminationrange and the achievement of the minimum illumination range may also bevaried in this case.

As explained above, it is also possible that the time interval for thetransition from one total light pattern to another total light patternis specified by control unit 16. This time interval is transmitted fromcontrol unit 16 to timer 27. The time interval, in particular, defines aswitchover from first total light pattern 39 or from third total lightpattern 41 to second total light pattern 40.

FIG. 21 shows a diagram which represents, as a %/s unit, the change inillumination range ΔLW/per time unit as a function of the vehicleacceleration. In this case, 0% means that illumination range LWcorresponds to the illumination range of a low beam, and 100%corresponds to the illumination range of a high beam functionality. A100% change per second in the illumination range thus causes a timeinterval ΔT of one second for the switch from one illumination range fora low beam functionality, to an illumination range for a maskedpermanent high beam. Accordingly, a change of 20%/per second in theillumination range means a time interval ΔT of five seconds until themasked permanent high beam has been activated completely.

The change in illumination range ΔLW, and thus time interval ΔT for theswitch from one total light pattern to another total light pattern, isable to be calculated from acceleration B in the following manner:

ΔLW=B·k ₃

where k₃

${10\frac{\% \mspace{14mu} s}{m}} \leq k_{3} \leq {200\frac{\% \mspace{14mu} s}{m}}$

in particular,

${40\frac{\% \mspace{14mu} s}{m}} \leq k_{3} \leq {80\frac{\% \mspace{14mu} s}{m}}$

and where preferably

$k_{3} = {50\frac{\% \mspace{14mu} s}{m}}$

and where

${20\frac{\% \;}{s}} \leq {\Delta \; L\; W} \leq {150\frac{\% \;}{s}}$

The manner in which delay unit 26 determines a time interval Tv, bywhich the switchover between two total light patterns or twoillumination states of a total light pattern is defined as a function ofthe detection rate of other road users 11, 12, will be described in thefollowing text with reference to FIG. 22. The data pertaining to theoccurrence and positions of other road users 11, 12 are transmitted byimage-processing unit 15 to delay unit 26 via control unit 16 andvehicle bus 17. Control unit 16 processes the delay time transmitted bydelay unit 26 such that a switchover operation is delayed by this timeinterval Tv.

The following text describes one example in which delay unit 26 definesa time interval Tv for the delay time for a switchover from first totallight pattern 39, i.e., a low beam, for instance, to second total lightpattern 40, i.e., a masked permanent high beam, for example. Delay unit26 is equipped with a signal transmitter 45 for this purpose, whichdetects a switch from second total light pattern 40 to first total lightpattern 39 and outputs a signal to a switch 46 with each switchover. Ineach switchover from second total light pattern 40 to first total lightpattern 39, the signal from signal transmitter 45 operates switch 46,such that a positive time value, which is generated by a timeincrementer 47, is applied at its first input. In such a switch, forinstance, a time value of 7 seconds may be applied at the first input ofswitch 46, which then forwards this value to its output.

Following a signal from signal transmitter 45 and the one-timetransmission of the time value of time incrementer 47, switch 46switches to a second input, which is connected to the output of afurther switch 48. Switch 48 is connected to an additional signaltransmitter 49. Signal transmitter 49 detects whether first total lightpattern 39 is active. If this is the case, it switches the first inputof switch 48 to the output of a first time transmitter 50 for areduction rate. This first time timer 50 continually supplies a certainnegative time value per time unit to the first input of switch 48. Forinstance, timer 50 outputs a reduction rate of −0.3 s⁻¹ to the firstinput of switch 48, which forwards this value to the second input ofswitch 46, via its output.

If signal transmitter 49 detects that first total light pattern 39 isnot active, it switches switch 48 to the second input, which isconnected to a second timer 51 for the reduction rate. Second timer 51induces a more rapid reduction of the delay time. For instance, thesecond timer continually transmits a reduction rate of −0.8 s^(−1,) tothe second input of switch 48, which is forwarded to the second input ofswitch 46 when first total light pattern 39 is not active.

The time values generated at the output of switch 46 are transmitted toan integrator 52, which adds up the values. However, integrator 52 has alimit for delay time Tv. Delay Tv may lie only in a region between 2seconds and 200 seconds. Delay time Tv is output by integrator 52. Delayunit 26 transmits this delay time Tv to control unit 16.

It is pointed out that signal transmitter 45 detects a switch fromsecond total light pattern 40 to first total light pattern 39 inparticular when another road user, e.g., an oncoming vehicle 11 or avehicle 12 traveling ahead, has been detected on the adjacent road lane.Delay time Tv thus is dependent on the detection rate of other roadusers. As an alternative, however, it is also possible that signaltransmitter 45 outputs a signal to switch 46 when another road user hasbeen newly detected, regardless of an actual change in the total lightpattern. This other, newly detected road user in particular is apreceding vehicle 12 which travels on the adjacent lane and passes ownvehicle 10, or it is an oncoming vehicle 11, which leaves the detectionrange of the camera and drives past the own vehicle.

Delay time Tv may be used not only for a delay in the switch between twototal light patterns, but also in the switch between two illuminationstates of a total light pattern. As described above, for instance,second total light pattern 40, i.e., the masked permanent high beam, mayhave two illumination states. In a first standard illumination state, acorridor is formed for a detected road user or a plurality of detectedroad users 11, 12, in front of which a center region M having a lowerillumination range is formed, and laterally adjacent thereto, sideregions S₁ and S₂ having a greater illumination range (see FIGS. 14 and15). In another illumination state, for instance, it is possible todispense with left side region S₂ (in right-hand traffic). The sameillumination range as in center region M is then provided in thisregion. In such a case, as discussed with reference to FIGS. 16 and 17,it is not necessary to control the illumination range in the left regionas a function of the horizontal angle Φ relative to a detected roaduser. If, for example, signal transmitter 45 detects an oncoming vehicle11 too frequently in such a case, the illumination range in side regionS₂ is no longer controlled as a function of horizontal angle Φ relativeto an oncoming vehicle 11, but the enlargement of the illumination rangein region S₂ is delayed by time interval Tv, once an oncoming vehicle 11has driven past own vehicle 10. If new oncoming vehicles 12 have beendetected within this time interval Tv, and signal transmitter 45therefore forwards the time value of time incrementer 47 to integrator52 as discussed with reference to FIG. 22, the illumination range inside region S₂ will remain minimal for a longer period of time insteadof being set to a higher value in the meantime.

Control unit 16 furthermore may determine under which conditions aswitch between two total light patterns or two illumination states of atotal light pattern will take place to begin with. In the decision as towhether a switch will be implemented at all, control unit 16 mayconsider the statistics of the detected road users and/or the temporaldevelopment of the steering angle. This will be explained in thefollowing text using the switch between second total light pattern 40and third total light pattern 41, with reference to FIG. 23.

Image-processing unit 15 transmits a signal to control unit 16 if a newroad user such as a new vehicle, for example, has been detected. Thissignal is transmitted to switch 57 as control signal. Switch 57 thenswitches through the upper first input shown in FIG. 23, which isconnected to the output of logic unit 56. Logic unit 56 has two inputs,via which step sizes are supplied. The first input is used forforwarding a position-dependent step size to logic unit 56. The positionof the object transmitted from image-processing unit 15 is forwarded toa position-dependent first step size incrementer 53 for this purpose,which, by a characteristic curve, assigns a step size to the position ofthe new object and outputs it to logic unit 56. A speed-dependent stepsize is forwarded to the second input of logic unit 56. Toward this end,speedometer 54 forwards the current vehicle speed to a speed-dependentsecond step size incrementer 55. Based on a characteristic curve, secondstep size incrementer 55 determines a step size as a function of thevehicle speed and transmits it to logic unit 56. Logic unit 56determines the maximum step size that was transmitted via the twoinputs, and transmits this maximum step size to first input of switch57, from where it is forwarded to an integrator 59.

Switch 57 subsequently switches to the second input—shown at the bottomin FIG. 23—which is connected to a speed-dependent step size decrementer58. Using speedometer 54, the current vehicle speed is forwarded to stepsize decrementer 58 as well. Step size decrementer 58 uses acharacteristic curve to determine a step size value by which the stepsize of integrator 59 is to be decremented per time unit. In otherwords, step size decrementer 58 specifies a speed-dependent decreaserate for the step size.

The step size determined by integrator 59 may be restricted to a rangeof 30 to 300, for instance. The decrease rate specified by step sizedecrementer 58 may lie in a range of −40 to 30 per second in this case.

In addition, speed-dependent shifting of the step size value takes placein order to directly influence the activation and deactivationthresholds for third total light pattern 41 via the vehicle speed. To doso, speedometer 54 furthermore forwards the current speed to shift unit61, which uses a characteristic curve to define a shift for the stepsize. The step size output by integrator 59 is forwarded to a positiveinput of a computing element 60, which transmits the step size output byshift unit 61 to a negative input of computing element 60. Computingelement 60 subtracts the step size transmitted by shift unit 61 from thestep size output by integrator 59 and outputs the result to a hysteresisunit 62, Hysteresis unit 62 specifies the switchover thresholds, so thatexcessive switching between the two total light pattern is prevented.

Finally, a characteristics signal either for second or third total lightpattern 40, 41 is output via first output unit 63, as a function of thestep size output by computing element 60. Control unit 16 is able tocontrol the headlamp system as a function of this characteristicssignal. However, it is also possible that it additionally considerssteering angle changes of vehicle 10, as will be explained in thefollowing text.

In such a case, the steering angle of the vehicle is continuouslydetected with the aid of a steering angle detection unit 64. Thedetected steering angle is forwarded to a generating unit 65 forgenerating a weighting factor. Generating unit 65 outputs a weightingfactor, determined as a function of the steering angle, to the firstinput of a logic unit 66.

In addition, the speed determined by speedometer 54 is transmitted to asecond generating unit 67 for generating an additional weighting factor.Using a characteristic curve, this unit 67 generates a weighting factor,which is transmitted to the second input of logic unit 66. Logic unit 66determines which one of the two transmitted weighting factors is thesmaller one and forwards it to the first input of a weighting unit 68.

The steering angle determined by steering angle detection unit 64 isforwarded to a differentiator 69, which determines the temporal steeringangle change. The absolute value of the angular change is determined incomputing element 70 and forwarded to the second input of weighting unit68. Thus, weighting unit 68 determines a characteristic quantity as afunction of characteristic curves for the vehicle speed and as afunction of the steering angle or the steering angle change, thecharacteristic quantity being forwarded to a positive input of anothercomputing element 71. Speedometer 54 also forwards the current vehiclespeed to a threshold value generator 72, which generates aspeed-dependent threshold value with the aid of a characteristic curve,and forwards it to a negative input of computing element 71. Incomputing element 71, the threshold value is subtracted from thecharacteristic quantity and the result is transmitted to an integrator73. The threshold value generated by threshold value generator 72 isselected in such a way that for no or only a slight variation in thesteering angle, an input value for weighting unit 71 results whicheffects a decrease in the characteristic value ascertained by integrator73. The threshold for reducing the characteristic quantity for thesteering angle change determined by integrator 73 lies in a rangebetween 2° per second to 3° per second.

The characteristic quantity integrated by integrator 73 reflects achange in the steering angle. Integrator 73 transmits the determinedsteering angle change to a hysteresis unit 74, which realizes activationand deactivation thresholds for the switchover operation in an effort toprevent excessive back-and-forth switching. Hysteresis unit 74, forexample, is adjusted so as to bring about a switchover from second totallight pattern 40 to third total light pattern 41 above integratedsteering angle changes of approximately 200 degrees. If the integratedsteering angle change is below approximately 100 degrees, then thesecond total light pattern becomes active again. Hysteresis unit 74outputs an identifying signal via second output unit 75, whichcharacterizes either second or third total light pattern 40, 41.

With the aid of first output unit 63 or with the aid of second outputunit 75, control unit 16 is able to determine which total light patternis to be triggered. In addition, a further logic unit 76 may be providedin control unit 16, to which the identifying signals of first outputunit 63 and second output unit 75 are transmitted. Using these two inputsignals, logic unit 76 determines an identifying signal, which is outputvia third output unit 77. In this case, an identifying signal for thirdtotal light pattern 41 is generated when such an identifying signal isoutput by first output unit 63 or second output unit 75. Control unit 16may then use this identifying signal to generate the corresponding totallight pattern by means of the headlamp system.

LIST OF REFERENCE CHARACTERS

1 right headlamp

2 left headlamp

3 light source

|4 housing

5 light disk

6 reflector

7 projection lens

8 first diaphragm

8 a shading edge of first diaphragm

9 second diaphragm

9 a shading edge of second diaphragm

10 vehicle having the headlamp system

11 oncoming vehicle

12 preceding vehicle

13 control unit for the right headlamp

14 control unit for the left headlamp

15 image-processing unit (device for detecting other road users)

16 control unit

17 vehicle bus

18 camera

19 first actuator for the right headlamp

20 second actuator for the right headlamp

21 third actuator for the right headlamp

22 first actuator for the left headlamp

23 second actuator for the left headlamp

24 third actuator for the left headlamp

25 device for detecting the driving behavior

26 delay unit

27 timer

28 navigation device

29 GPS receiver

30 center axis

31 extraction unit

32 classifier

33 confidence unit

34 assignment unit

35 horizontal plane

36 center axis

37 horizontal axis

38 vertical axis

39 first total light pattern/permanent low beam

40 second total light pattern/masked high beam

41 third total light pattern/sliding illumination range

42 15° increase in the first total light pattern

43 illumination range

44 illumination range

45 signal transmitter

46 46 switch

47 time incrementer

48 switch

49 signal transmitter

50 first timer for decrease rate

51 second timer for decrease rate

52 integrator

53 position-dependent first step size incrementer

54 speedometer

55 position-dependent second step size incrementer

56 logic unit

57 switch

58 position-dependent step size incrementer

59 integrator

60 computing element

61 shift unit

62 hysteresis unit

63 first output unit

64 steering angle detection unit

65 first weighting factor generating unit

66 logic unit

67 second weighting factor generating unit

68 weighting unit

69 differentiator

70 computing element

73 threshold value generator

100/-170 method steps

180/-280 method steps

1-10. (canceled)
 11. A method for controlling a headlamp system of avehicle, comprising: detecting road users in front of the vehicle in adriving direction; controlling a light pattern produced by the headlampsystem to have an illumination range in a direction of at least onedetected road user that is less than a distance to the detected roaduser and an illumination range in another direction that is greater thanthe distance to the detected road user; wherein the illumination rangein the other direction is controlled as a function of a horizontal anglebetween the driving direction of the vehicle and a connecting line fromthe vehicle to the detected road user or to another detected road user.12. The method according to claim 11, wherein the illumination range inthe other direction is in an inverse relationship with the horizontalangle.
 13. The method according to claim 11, wherein the followingrelationship is satisfied:LW=Lmax(−mΦ+n), LW representing the illumination range in the otherdirection, Lmax representing a maximum illumination range, Φrepresenting the horizontal angle, and the following applying to m:0.167 degrees−1≦m≦1.2 degrees−1 and the following applying to n:1≦n≦1.2.
 14. The method according to claim 11, wherein for horizontalangles in a range of 0 degrees to 2 degrees or in a range of 0.2 degreesto 0.8 degrees, the illumination range in the other directioncorresponds to a maximum illumination range.
 15. The method according toclaim 11, wherein for horizontal angles in a range of 3 degrees to 6degrees or in a range of 4 degrees to 5 degrees, the illumination rangein the other direction corresponds to a minimum illumination range. 16.The method according to claim 11, wherein the illumination range in theother direction is controlled as a function of the horizontal anglebetween the driving direction of the vehicle and the connecting linefrom the vehicle to the additional detected road user, and the lightpattern in the other direction illuminates an oncoming road lane. 17.The method according to claim 11, wherein the illumination range in theother direction is controlled as a function of the horizontal anglebetween the driving direction of the vehicle and the connecting linefrom the vehicle to the detected road user, and in a passing maneuver,the light pattern in the other direction illuminates a region adjacentto a road lane of the detected road user.
 18. The method according toclaim 17, wherein the illumination range in the other direction iscontrolled after a turn signal indicator for a passing maneuver in adirection of an oncoming road lane has been activated.
 19. The methodaccording to claim 11, wherein in the light pattern in the direction ofthe detected road user, a center region having a lower illuminationrange is formed, and side regions having a greater illumination rangeare formed on both sides adjacent to the center region, the illuminationrange in a side region being controlled as a function of the horizontalangle between the driving direction of the vehicle and the connectingline of the vehicle with the detected road user or an additionaldetected road user.
 20. A headlamp system for a vehicle, comprising: atleast two headlamps, set apart from each other, adapted to generate atotal light pattern; a road user detection device adapted to detect aroad user in front of the vehicle in a driving direction; and a controlunit coupled to the road user detection device and adapted to producethe total light pattern, the total light pattern having an illuminationrange in a direction of at least one detected road user that is lessthan a distance to the detected road user and having an illuminationrange in another direction that is greater than the distance to thedetected road user; wherein the control unit is adapted to control theheadlamps to control the illumination range in the other direction as afunction of a horizontal angle between the driving direction of thevehicle and a connecting line from the vehicle to the detected road useror to another detected road user.